staging: lustre: lnet: Do not drop message when shutting down LNet

There is a case in lnet_parse() where we discover that LNet
is shutting down but we continue to use the NI when we drop the
message and end up calling ko2iblnd_check_send_locked() which tries to
allocate from the Tx pool which has been cleaned up already.
This triggers a NULL pointer dereference.

This fix just returns from lnet_parse() when we disover LNet is
shutting down.

Signed-off-by: Doug Oucharek <doug.s.oucharek@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8106
Reviewed-on: http://review.whamcloud.com/19993


Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>