drm/imagination: Propagate map failures correctly from pvr_mmu_map_sgl()

In the Linux kernel, the following vulnerability has been resolved:

drm/imagination: Propagate map failures correctly from pvr_mmu_map_sgl()

Map failure from pvr_mmu_map_sgl() interface was not returned correctly
to pvr_mmu_map() interface. This resulted in pvr_mmu_map() interface to
continue instead of returning an error to caller.
Fix it by returning a proper error code from pvr_mmu_map_sgl() interface.

Call stack for crash:
[ 1179.286237] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
[ 1179.295067] Mem abort info:
[ 1179.297877] ESR = 0x0000000096000004
[ 1179.301656] EC = 0x25: DABT (current EL), IL = 32 bits
[ 1179.306987] SET = 0, FnV = 0
[ 1179.310048] EA = 0, S1PTW = 0
[ 1179.313198] FSC = 0x04: level 0 translation fault
[ 1179.318096] Data abort info:
[ 1179.320993] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[ 1179.326483] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 1179.331546] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 1179.336895] user pgtable: 4k pages, 48-bit VAs, pgdp=000000009822a000
[ 1179.343402] [0000000000000008] pgd=0000000000000000, p4d=0000000000000000
[ 1179.350243] Internal error: Oops: 0000000096000004 [#2] SMP
[ 1179.355908] Modules linked in: powervr gpu_sched drm_shmem_helper drm_gpuvm drm_exec xhci_plat_hcd xhci_hcd dwc3 usbcore usb_common snd_soc_simple_card snd_soc_simple_card_utils dwc3_am62 at24 sa2ul sha512 libsha512 sha256 authenc sch_fq_codel fuse dm_mod ipv6
[ 1179.378992] CPU: 1 UID: 1000 PID: 680 Comm: deqp-vk Tainted: G D 6.17.0 #1 PREEMPT
[ 1179.388120] Tainted: [D]=DIE
[ 1179.390994] Hardware name: Texas Instruments AM625 SK (DT)
[ 1179.396467] pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 1179.403415] pc : pvr_mmu_op_context_unmap_curr_page+0x6c/0x134 [powervr]
[ 1179.410140] lr : pvr_mmu_op_context_unmap_curr_page+0x58/0x134 [powervr]
[ 1179.416848] sp : ffff8000839ab8c0
[ 1179.420153] x29: ffff8000839ab8c0 x28: 0000000000000001 x27: 000000008f386000
[ 1179.427283] x26: ffff000016d1df98 x25: 0000000000247000 x24: 00000000000001e6
[ 1179.434413] x23: 0000000000000002 x22: 000000000000ffff x21: 0000000000000247
[ 1179.441540] x20: 0000000000000245 x19: ffff000016d1df60 x18: 0000000000000002
[ 1179.448668] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001
[ 1179.455793] x14: 0000000000060810 x13: ffff80007fffffff x12: ffff000004190480
[ 1179.462921] x11: ffff8000853f7000 x10: ffff8000811ae000 x9 : ffff0000041900b8
[ 1179.470051] x8 : 0000000000000000 x7 : 00000000990c4001 x6 : 0000000000000007
[ 1179.477177] x5 : ffff000016d1df60 x4 : 0000000000000000 x3 : ffff00000a7d8000
[ 1179.484306] x2 : 00000000000001ff x1 : 0000000000000000 x0 : 0000000000000000
[ 1179.491433] Call trace:
[ 1179.493872] pvr_mmu_op_context_unmap_curr_page+0x6c/0x134 [powervr] (P)
[ 1179.500582] pvr_mmu_map+0x31c/0x388 [powervr]
[ 1179.505027] pvr_vm_gpuva_map+0x40/0x88 [powervr]
[ 1179.509732] __drm_gpuvm_sm_map+0x250/0x44c [drm_gpuvm]
[ 1179.514952] drm_gpuvm_sm_map+0x48/0x5c [drm_gpuvm]
[ 1179.519822] pvr_vm_bind_op_exec+0x64/0x70 [powervr]
[ 1179.524785] pvr_vm_map+0x1f8/0x2a8 [powervr]
[ 1179.529142] pvr_ioctl_vm_map+0x12c/0x188 [powervr]
[ 1179.534018] drm_ioctl_kernel+0xb8/0x128
[ 1179.537941] drm_ioctl+0x21c/0x4ec
[ 1179.541337] __arm64_sys_ioctl+0xac/0x108
[ 1179.545344] invoke_syscall+0x44/0x100
[ 1179.549091] el0_svc_common.constprop.0+0x40/0xe0
[ 1179.553790] do_el0_svc+0x1c/0x28
[ 1179.557106] el0_svc+0x34/0xf0
[ 1179.560159] el0t_64_sync_handler+0xd0/0xe4
[ 1179.564334] el0t_64_sync+0x198/0x19c
[ 1179.567996] Code: 54000300 35000360 f9402261 79409a62 (f9400421)
[ 1179.574081] ---[ end trace 0000000000000000 ]---