LU-11240 gnilnd: Replace KGNILND_BUILD_REV

LU-11240 gnilnd: Replace KGNILND_BUILD_REV

The current format of the gnilnd version string causes a compilation
error. Since gnilnd doesn't really need its own version string we just
replace it with LUSTRE_VERSION_STRING.

Cray-bug-id: LUS-6072
Test-Parameters: trivial
Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: I6f45df2566853a6f4c2078cf72c7eac7a52f3fad
Reviewed-on: https://review.whamcloud.com/32990
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Chuck Fossen <chuckf@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>