drm/xe: fix drm_gpusvm_init() arguments

The Xe driver fails to build when CONFIG_DRM_XE_GPUSVM is disabled
but CONFIG_DRM_GPUSVM is turned on, due to the clash of two commits:

In file included from drivers/gpu/drm/xe/xe_vm_madvise.c:8:
drivers/gpu/drm/xe/xe_svm.h: In function 'xe_svm_init':
include/linux/stddef.h:8:14: error: passing argument 5 of 'drm_gpusvm_init' makes integer from pointer without a cast [-Wint-conversion]
drivers/gpu/drm/xe/xe_svm.h:217:38: note: in expansion of macro 'NULL'
  217 |                                NULL, NULL, 0, 0, 0, NULL, NULL, 0);
      |                                      ^~~~
In file included from drivers/gpu/drm/xe/xe_bo_types.h:11,
                 from drivers/gpu/drm/xe/xe_bo.h:11,
                 from drivers/gpu/drm/xe/xe_vm_madvise.c:11:
include/drm/drm_gpusvm.h:254:35: note: expected 'long unsigned int' but argument is of type 'void *'
  254 |                     unsigned long mm_start, unsigned long mm_range,
      |                     ~~~~~~~~~~~~~~^~~~~~~~
In file included from drivers/gpu/drm/xe/xe_vm_madvise.c:14:
drivers/gpu/drm/xe/xe_svm.h:216:16: error: too many arguments to function 'drm_gpusvm_init'; expected 10, have 11
  216 |         return drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM (simple)", &vm->xe->drm,
      |                ^~~~~~~~~~~~~~~
  217 |                                NULL, NULL, 0, 0, 0, NULL, NULL, 0);
      |                                                                 ~
include/drm/drm_gpusvm.h:251:5: note: declared here

Adapt the caller to the new argument list by removing the extraneous
NULL argument.

Fixes: 9e97874 ("drm/xe/userptr: replace xe_hmm with gpusvm")
Fixes: 10aa5c8 ("drm/gpusvm, drm/xe: Fix userptr to not allow device private pages")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20251204094704.1030933-1-arnd@kernel.org
(cherry picked from commit 29bce9c)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

Author: arndb

drivers/gpu/drm/xe/xe_svm.h

@@ -214,7 +214,7 @@ int xe_svm_init(struct xe_vm *vm)
 {
 #if IS_ENABLED(CONFIG_DRM_GPUSVM)
 	return drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM (simple)", &vm->xe->drm,
-			       NULL, NULL, 0, 0, 0, NULL, NULL, 0);
+			       NULL, 0, 0, 0, NULL, NULL, 0);
 #else
 	return 0;
 #endif