drm: stash AGP include under the do-we-have-AGP ifdef

This fixes the MIPS with DRM build.

Signed-off-by: Eric Anholt <eric@anholt.net>
Tested-by: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_agpsupport.c

@@ -33,10 +33,11 @@
 
 #include "drmP.h"
 #include <linux/module.h>
-#include <asm/agp.h>
 
 #if __OS_HAS_AGP
 
+#include <asm/agp.h>
+
 /**
  * Get AGP information.
  *