LU-14877 llite: Remove inode locking in ll_fsync

LU-14877 llite: Remove inode locking in ll_fsync

It does not appear to be necessary

Change-Id: I0142a9dca4ecc6893521275b69a0a46012eab0b0
Fixes: 8f3ef1e961 ("LU-812 llite: 3.0+ kernel fsync should call write")
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/44368
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Wang Shilong <wangshilong1991@gmail.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>