LU-5420 ptlrpc: revert ptlrpc_reconnect_import() changes

LU-5420 ptlrpc: revert ptlrpc_reconnect_import() changes

Revert the changes from LU-4913 in ptlrpc_reconnect_import()
(commit cae32fb38f0754ab2f8eae89ffe9151c6c194ef8) that are
causing intermittent MDS startup problems due to an inability
to reconnect to MGS if it is sharing the same OSD.  The MGS
connection has historically been pretty different from other
kinds of ptlrpc connections.

Work in LU-5420 will continue to better unify these different
connection options meanwhile, so this is not really a final fix,
just merely a way to bring things back into stable state in time
for 2.7.0 release.

Change-Id: I72aa43332dade8f3fc67a028cd4685f9f4383953
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: http://review.whamcloud.com/13838
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>