gpu: add module.h to drivers/gpu files as required.

So that we don't get build failures once the implicit module.h
presence is removed.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 2ec7d48..4911e1d 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -37,6 +37,7 @@
 #include "drmP.h"
 #include <linux/poll.h>
 #include <linux/slab.h>
+#include <linux/module.h>
 
 /* from BKL pushdown: note that nothing else serializes idr_find() */
 DEFINE_MUTEX(drm_global_mutex);