LU-12756 lnet: Refactor lnet_set_non_mr_pref_nid

Replace lnet_send_data argument.

The sd_send_case check can be removed because all call paths already
satisfy this condition.

Test-Parameters: trivial
Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: I95707c7457edef44eec7d00bde93f731545f8c4e
Reviewed-on: https://review.whamcloud.com/36537
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexandr Boyko <c17825@cray.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Neil Brown <neilb@suse.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>