eCryptfs: Use DEFINE_MUTEX() for mutex lock
mutex lock can be initialized automatically with DEFINE_MUTEX()
rather than explicitly calling mutex_init().
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: Tyler Hicks <code@tyhicks.com>
authored by