LU-16796 lnet: Change sfw_session to use refcount_t

LU-16796 lnet: Change sfw_session to use refcount_t

This patch changes struct sfw_session to use
refcount_t instead of atomic_t

This patch also address checkpatch errors.

Test-Parameters: trivial testlist=lnet-selftest
Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: Ifa77b8d9280756ce52c8f59d1d193a866f0ba8a7
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/53438
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>