LU-8025 llite: make vvp_io_write_start lockless for newer kernels

When support for newer kernels was backported from the
upstream kernel it lacked any of the enhancements done
for newer version of lustre. This work makes the newer
kernel support lockless writes like the rest of the
lustre llite code.

Change-Id: I6ea32dbb3097aea3e2031e1121e238e549bccc9b
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Signed-off-by: Ben Evans <bevans@cray.com>
Reviewed-on: http://review.whamcloud.com/19840
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>