drm/ttm: Fix build on architectures without AGP

Make inclusion of <asm/agp.h> conditional on TTM_HAS_AGP. The use of the functions declared in it is already conditional.

---
 drivers/gpu/drm/ttm/ttm_page_alloc.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

index b1d67dc..1f32b46 100644
@@ -40,7 +40,9 @@
 #include <linux/slab.h>
 
 #include <asm/atomic.h>
+#ifdef TTM_HAS_AGP
 #include <asm/agp.h>
+#endif
 
 #include "ttm/ttm_bo_driver.h"
 #include "ttm/ttm_page_alloc.h"

1.7.1