LU-8654 obd: access ocd_connect_flags2 only when present

LU-8654 obd: access ocd_connect_flags2 only when present

Before 2.7.50 clients will send a struct obd_connect_data_v1 rather
than a full struct obd_connect_data. So check for OBD_CONNECT_FLAGS2
before accessing the ocd_connect_flags2 member of struct
obd_connect_data.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: Ic1c2b54be9b3cbaec9af894f204663c74fa41213
Reviewed-on: http://review.whamcloud.com/22837
Tested-by: Jenkins
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>