drm: Pass pointers to virt_to_page()

Most architectures define virt_to_page() as a macro that casts its
argument such that an argument of type unsigned long will be accepted
without complaint.  However, the proper type is void *, and passing
unsigned long results in a warning on MIPS.

Compile-tested only.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index 8ef6503..93e95d7 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -301,7 +301,7 @@
 
 	offset = (unsigned long)vmf->virtual_address - vma->vm_start;	/* vm_[pg]off[set] should be 0 */
 	page_nr = offset >> PAGE_SHIFT; /* page_nr could just be vmf->pgoff */
-	page = virt_to_page(dma->pagelist[page_nr]);
+	page = virt_to_page((void *)dma->pagelist[page_nr]);
 
 	get_page(page);
 	vmf->page = page;