LU-2923 ptlrpc: Stop suppressing pings when IR is unavailable

Currently, IR does not notify LWPs and MDT-MDT OSPs of target
recoveries.  This patch removes OBD_CONNECT_PINGLESS from LWP and
MDT-MDT OSP connect requests.

Although an MGC does not know if IR is administratively disabled on
the MGS or if a particular target is mounted with "noir", it can
detect MGSs that do not support IR at all and MGSs that are
unreachable.  This patch stops suppressing pings under those two
cases.

As a cleanup requested by the reviewers, this patch also replaces the
plain OBD_CONNECT_PINGLESS checks with OCD_HAS_FLAG(..., PINGLESS)
macros.

Change-Id: I993b46c8f33413793d9cf2fa1a73b3635996a206
Signed-off-by: Li Wei <wei.g.li@intel.com>
Reviewed-on: http://review.whamcloud.com/5900
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Tested-by: Hudson
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>