ceph: update i_max_size even if inode version does not change

handle following sequence of events:
 - client releases a inode with i_max_size > 0. The release message
   is queued. (is not sent to the auth MDS)
 - a 'lookup' request reply from non-auth MDS returns the same inode.
 - client opens the inode in write mode. The version of inode trace
   in 'open' request reply is equal to the cached inode's version.
 - client requests new max size. The MDS ignores the request because
   it does not affect client's write range

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