LU-13930 pcc: auto PCC-RO attach in atomic_open

LU-13930 pcc: auto PCC-RO attach in atomic_open

Auto PCC-RO attach during PCC open will try to change the layout
into read-only state on MDT. If the intent open in atomic_open
returns a lock with MDS_INODELOCK_LAYOUT bit set, it may cause
dead lock on lock blocking callback caused by the layout change
into read-only state on MDT. Thus it would better to release the
open intent lock frist before call PCC open.

Test-Parameters: clientcount=3 testlist=sanity-pcc,sanity-pcc,sanity-pcc
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: I7ab86bd56da9bacc40b201162ffd022ab5a2352c