drm/xe/vm: Fix SVM leak on resv obj alloc failure in xe_vm_create()

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

drm/xe/vm: Fix SVM leak on resv obj alloc failure in xe_vm_create()

Commit 9e9787414882 ("drm/xe/userptr: replace xe_hmm with gpusvm") made
xe_svm_init() unconditional in xe_vm_create() and extended it to also
initialize a "simple" gpusvm state for non-fault-mode VMs. The matching
xe_svm_fini() call in xe_vm_close_and_put() was updated to run
unconditionally, but the error unwind path in xe_vm_create() was not.

On the drm_gpuvm_resv_object_alloc() failure path, xe_svm_init() has
already succeeded but xe_svm_fini() is only called when
XE_VM_FLAG_FAULT_MODE is set. For non-fault-mode VMs this leaves
vm->svm.gpusvm partially initialized and leaks the resources allocated
by drm_gpusvm_init().

For fault-mode VMs, xe_svm_init() additionally acquires the pagemap
owner via drm_pagemap_acquire_owner() and the pagemaps via
xe_svm_get_pagemaps(). Those resources are released by xe_svm_close(),
not xe_svm_fini(). On the same error path, xe_svm_close() is not
called either, so fault-mode VMs leak the pagemap owner and pagemaps.

Fix both leaks:

- Call xe_svm_fini() unconditionally on the err_svm_fini path, matching
the unconditional xe_svm_init() call. Move the vm->size = 0
assignment out of the conditional so the xe_vm_is_closed() assert in
xe_svm_fini() (and xe_svm_close()) holds for both modes.

- Call xe_svm_close() for fault-mode VMs before xe_svm_fini(), matching
the ordering used in xe_vm_close_and_put().

(cherry picked from commit ca2a3587d577ba764e0fe628fb676244fc33ddd4)