LU-9859 libcfs: move files out of libcfs/linux

LU-9859 libcfs: move files out of libcfs/linux

Files that are not used to handle various kernel verisons are
promoted out of the linux directory. Loosely based on

Linux-commit: f72c3ab791ac0b2b75b5b5d4d51d8eb89ea1e515

This bring us more into sync with linux lustre client.

Change-Id: I4aad42671de14b4e5ca0743d2126363c829b0d74
Test-Parameters: trivial
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/37191
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.super@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>