LU-9859 libcfs: move tracefile locking from linux-tracefile.c

LU-9859 libcfs: move tracefile locking from linux-tracefile.c
 to tracefile.c

There is no value in keeping it separate.

Linux-commit: 49209c598d93289ca077575615e98f242b1d8156

Test-Parameters: trivial

Change-Id: I24ee7545a40fd6d2ac15018f089d51142736fa27
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-on: https://review.whamcloud.com/37408
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Neil Brown <neilb@suse.de>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>