MRP-2275 kernel: restore SL7/CentOS7 client support

New kernel switches from fl_* to lm_* names in
struct lock_manager_operations.

Change-Id: Ica187edfa871f58a8669196cbfec30bf04a89474
Signed-off-by: Andriy Skulysh <andriy.skulysh@seagate.com>
Reviewed-on: http://es-gerrit.xyus.xyratex.com:8080/4607
Tested-by: Jenkins
Reviewed-by: Alexander Boyko <alexander.boyko@seagate.com>
Tested-by: Elena Gryaznova <elena.gryaznova@seagate.com>
Reviewed-by: Vitaly Fertman <vitaly.fertman@seagate.com>