mds: pass proper mask to CInode::get_caps_issued

There is a total of 22 cap bits and file lock uses 8 cap bits.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
mds: change XLOCK/XLOCKDONE's next state to LOCK

For simplelock and filelock, XLOCK/XLOCKDONE's next state is SYNC.
But filelock in XLOCK/XLOCKDONE state allow Fb caps, filelock in
SYNC state does not. So filelock can be stuck in XLOCK/XLOCKDONE
state forever if there are Fb caps issued.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>