drm/gem-dma: Test for imported buffers with drm_gem_is_imported()

Instead of testing import_attach for imported GEM buffers, invoke
drm_gem_is_imported() to do the test.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Anusha Srivatsa <asrivats@redhat.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250226172457.217725-3-tzimmermann@suse.de

Author: tdz

drivers/gpu/drm/drm_gem_dma_helper.c

@@ -228,7 +228,7 @@ void drm_gem_dma_free(struct drm_gem_dma_object *dma_obj)
 	struct drm_gem_object *gem_obj = &dma_obj->base;
 	struct iosys_map map = IOSYS_MAP_INIT_VADDR(dma_obj->vaddr);
 
-	if (gem_obj->import_attach) {
+	if (drm_gem_is_imported(gem_obj)) {
 		if (dma_obj->vaddr)
 			dma_buf_vunmap_unlocked(gem_obj->import_attach->dmabuf, &map);
 		drm_prime_gem_destroy(gem_obj, dma_obj->sgt);