LU-6142 obdclass: checkpatch cleanup of obd_mount_server.c

LU-6142 obdclass: checkpatch cleanup of obd_mount_server.c

Address the many issues reported by checkpatch.pl. Replace __u**
with u** since it is kernel only code. Move lustre_tgt
registeration from obd_mount.c to obd_mount_server.c.

Change-Id: If06d120434ecb200f7a265167a537b2c98519670
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/47259
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>