drm: Make drm_vm_open/close_locked private to drm_vm.c

It's only used for legacy mmaping support now.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461691808-12414-8-git-send-email-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index f90bd5f..ac9f4b3 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -395,16 +395,8 @@
 	.close = drm_vm_close,
 };
 
-/**
- * \c open method for shared virtual memory.
- *
- * \param vma virtual memory area.
- *
- * Create a new drm_vma_entry structure as the \p vma private data entry and
- * add it to drm_device::vmalist.
- */
-void drm_vm_open_locked(struct drm_device *dev,
-		struct vm_area_struct *vma)
+static void drm_vm_open_locked(struct drm_device *dev,
+			       struct vm_area_struct *vma)
 {
 	struct drm_vma_entry *vma_entry;
 
@@ -429,8 +421,8 @@
 	mutex_unlock(&dev->struct_mutex);
 }
 
-void drm_vm_close_locked(struct drm_device *dev,
-		struct vm_area_struct *vma)
+static void drm_vm_close_locked(struct drm_device *dev,
+				struct vm_area_struct *vma)
 {
 	struct drm_vma_entry *pt, *temp;