staging: erofs: Fix spelling issue

Changed "stoped" to "stopped".

Signed-off-by: Aaron Strahlberger <aaron.strahlberger@posteo.de>
Signed-off-by: Julius Wiedmann <julius.wiedmann@fau.de>
Signed-off-by: Dominik Huber <domi250@gmx.de>
Reviewed-by: Gao Xiang <gaoxiang25@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>