mds: optimize revoking stale caps

mds: optimize revoking stale caps

For caps that are not being revoked and don't have writeable range
and don't want exclusive caps or file read/write. there is no need
to call Locker::revoke_stale_caps(Capability*). Because these caps
don't need recover and don't affect eval_gather()/try_eval().

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
(cherry picked from commit cb62030f0468fc04735c1b4cff73da779cb11ad8)

 Conflicts:
	src/mds/CInode.cc
	src/mds/Capability.h
	src/mds/Locker.cc
	src/mds/Migrator.cc