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.c b/drivers/gpu/drm/radeon/r600.c
index 12470b0..4e777c1 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -29,6 +29,7 @@
 #include <linux/seq_file.h>
 #include <linux/firmware.h>
 #include <linux/platform_device.h>
+#include <linux/module.h>
 #include "drmP.h"
 #include "radeon_drm.h"
 #include "radeon.h"