LU-13190 mds: send mbo_max_mdsize in open intent reply

LU-13190 mds: send mbo_max_mdsize in open intent reply

 - client sends open|create intent before a connection to OST
   cl_default_mds_easize is 0 since initialization
 - MDS replies back without UPDATE bit in LDLM lock, but wit EAh
    (MDS doesn't send OBD_MD_FLMODEASIZE and mbo_max_mdsize back
 - client's cl_default_mds_easize is still 0
 - client sends getattr intent with 0-size buffer for EA
 - MDS replies LAYOUT lock, but empty EA due to 0-size buffer
 - client sets local layout to EMPTY
 - all subsequent I/O fails with -EBADF

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: Iadd5595d956f0469e3916cdc1cca2ac8f802a149
Reviewed-on: https://review.whamcloud.com/37400
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>