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/radeon/r600_cp.c b/drivers/gpu/drm/radeon/r600_cp.c
index 45fd592..c9db493 100644
--- a/drivers/gpu/drm/radeon/r600_cp.c
+++ b/drivers/gpu/drm/radeon/r600_cp.c
@@ -26,6 +26,8 @@
  *     Alex Deucher <alexander.deucher@amd.com>
  */
 
+#include <linux/module.h>
+
 #include "drmP.h"
 #include "drm.h"
 #include "radeon_drm.h"