ecryptfs: remove unneeded buggy code in ecryptfs_do_create()
There is a bug in error handling of lock_parent() in ecryptfs_do_create():
lock_parent() acquries mutex even if dget_parent() fails, so mutex should be unlocked anyway.
But dget_parent() does not fail, so the patch just removes unneeded buggy code.
Found by Linux Driver Verification project (linuxtesting.org).