drm/nouveau: rename nouveau_drm.h to nouveau_drv.h

Fixes out-of-tree build issue where uapi/drm/nouveau_drm.h gets picked
up instead.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nv84_fence.c

@@ -22,7 +22,7 @@
  * Authors: Ben Skeggs
  */
 
-#include "nouveau_drm.h"
+#include "nouveau_drv.h"
 #include "nouveau_dma.h"
 #include "nouveau_fence.h"