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

"agpmem" is never NULL here.
Signed-off-by: NDan Carpenter <error27@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_memory.c

@@ -77,7 +77,7 @@ static void *agp_remap(unsigned long offset, unsigned long size,
 		    && (agpmem->bound + (agpmem->pages << PAGE_SHIFT)) >=
 		    (offset + size))
 			break;
-	if (!agpmem)
+	if (&agpmem->head == &dev->agp->memory)
 		return NULL;
 
 	/*