LU-8630 build: Fix definition of KMP_MODDIR

LU-8630 build: Fix definition of KMP_MODDIR

Without KMP_MODDIR defined, it won't be correctly replaced in
dkms.mkconf, thus causing dkms install of lustre to fail

Signed-off-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Change-Id: Ie671ede26b6cdf28aebeb80e131ff8506b9c05df
Reviewed-on: http://review.whamcloud.com/22663
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>