LU-6142 lnet: use list_first_entry() where appropriate.

LU-6142 lnet: use list_first_entry() where appropriate.

This patch changes
   list_entry(foo.next, ...)
to
   list_first_entry(&foo, ...)

in cases where 'foo' is a list head, rather than a list member.

Test-Parameters: trivial
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ied04412bf976d8fb219bb3c14c56879d2cf83ae7
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50827
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>