drivers/gpu/drm/drm_memory.c: fix check for end of loop

"agpmem" is never NULL here.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_memory.c b/drivers/gpu/drm/drm_memory.c
index e4865f9..7732268 100644
--- a/drivers/gpu/drm/drm_memory.c
+++ b/drivers/gpu/drm/drm_memory.c
@@ -77,7 +77,7 @@
 		    && (agpmem->bound + (agpmem->pages << PAGE_SHIFT)) >=
 		    (offset + size))
 			break;
-	if (!agpmem)
+	if (&agpmem->head == &dev->agp->memory)
 		return NULL;
 
 	/*