drm/ttm: use ffs in ttm_mem_type_from_place

A bit pointless to search for the first bit set manually.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/ttm/ttm_bo.c

@@ -57,14 +57,14 @@ static struct attribute ttm_bo_count = {
 static inline int ttm_mem_type_from_place(const struct ttm_place *place,
 					  uint32_t *mem_type)
 {
-	int i;
+	int pos;
 
-	for (i = 0; i <= TTM_PL_PRIV5; i++)
-		if (place->flags & (1 << i)) {
-			*mem_type = i;
-			return 0;
-		}
-	return -EINVAL;
+	pos = ffs(place->flags & TTM_PL_MASK_MEM);
+	if (unlikely(!pos))
+		return -EINVAL;
+
+	*mem_type = pos - 1;
+	return 0;
 }
 
 static void ttm_mem_type_debug(struct ttm_bo_device *bdev, int mem_type)