staging: lustre: lnet: remove LNET_MUTEX_LOCK macro

LNET_MUTEX_LOCK and LNET_MUTEX_UNLOCK are verbose wrappers to mutex_lock and
mutex_unlock.  Get rid of these.

Signed-off-by: Mike Shuey <shuey@purdue.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>