LU-12678 lnet: change ksocknal_create_peer() to return pointer

LU-12678 lnet: change ksocknal_create_peer() to return pointer

ksocknal_create_peer() currently returns an error status, and if that
is 0, a pointer is stored in a by-reference argument.  The preferred
pattern in the kernel is to return the pointer, or the error code
encoded with ERR_PTR().

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ie1458851e93ff56236fe7ac914e9fdfb0b079d0b
Reviewed-on: https://review.whamcloud.com/36833
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <hornc@cray.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>