vdpa_sim: fix possible memory leak in vdpasim_net_init() and vdpasim_blk_init()

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

vdpa_sim: fix possible memory leak in vdpasim_net_init() and vdpasim_blk_init()

Inject fault while probing module, if device_register() fails in
vdpasim_net_init() or vdpasim_blk_init(), but the refcount of kobject is
not decreased to 0, the name allocated in dev_set_name() is leaked.
Fix this by calling put_device(), so that name can be freed in
callback function kobject_cleanup().

(vdpa_sim_net)
unreferenced object 0xffff88807eebc370 (size 16):
comm "modprobe", pid 3848, jiffies 4362982860 (age 18.153s)
hex dump (first 16 bytes):
76 64 70 61 73 69 6d 5f 6e 65 74 00 6b 6b 6b a5 vdpasim_net.kkk.
backtrace:
[<ffffffff8174f19e>] __kmalloc_node_track_caller+0x4e/0x150
[<ffffffff81731d53>] kstrdup+0x33/0x60
[<ffffffff83a5d421>] kobject_set_name_vargs+0x41/0x110
[<ffffffff82d87aab>] dev_set_name+0xab/0xe0
[<ffffffff82d91a23>] device_add+0xe3/0x1a80
[<ffffffffa0270013>] 0xffffffffa0270013
[<ffffffff81001c27>] do_one_initcall+0x87/0x2e0
[<ffffffff813739cb>] do_init_module+0x1ab/0x640
[<ffffffff81379d20>] load_module+0x5d00/0x77f0
[<ffffffff8137bc40>] __do_sys_finit_module+0x110/0x1b0
[<ffffffff83c4d505>] do_syscall_64+0x35/0x80
[<ffffffff83e0006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

(vdpa_sim_blk)
unreferenced object 0xffff8881070c1250 (size 16):
comm "modprobe", pid 6844, jiffies 4364069319 (age 17.572s)
hex dump (first 16 bytes):
76 64 70 61 73 69 6d 5f 62 6c 6b 00 6b 6b 6b a5 vdpasim_blk.kkk.
backtrace:
[<ffffffff8174f19e>] __kmalloc_node_track_caller+0x4e/0x150
[<ffffffff81731d53>] kstrdup+0x33/0x60
[<ffffffff83a5d421>] kobject_set_name_vargs+0x41/0x110
[<ffffffff82d87aab>] dev_set_name+0xab/0xe0
[<ffffffff82d91a23>] device_add+0xe3/0x1a80
[<ffffffffa0220013>] 0xffffffffa0220013
[<ffffffff81001c27>] do_one_initcall+0x87/0x2e0
[<ffffffff813739cb>] do_init_module+0x1ab/0x640
[<ffffffff81379d20>] load_module+0x5d00/0x77f0
[<ffffffff8137bc40>] __do_sys_finit_module+0x110/0x1b0
[<ffffffff83c4d505>] do_syscall_64+0x35/0x80
[<ffffffff83e0006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0