ttm/ttm_device.h: fix a trival typo

should replace '@' with '*'
Signed-off-by: suijingfeng <suijingfeng@loongson.cn>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230303101216.788971-1-15330273260@189.cn

include/drm/ttm/ttm_device.h

@@ -141,7 +141,7 @@ struct ttm_device_funcs {
 	 * the graphics address space
 	 * @ctx: context for this move with parameters
 	 * @new_mem: the new memory region receiving the buffer
-	 @ @hop: placement for driver directed intermediate hop
+	 * @hop: placement for driver directed intermediate hop
 	 *
 	 * Move a buffer between two memory regions.
 	 * Returns errno -EMULTIHOP if driver requests a hop