LU-6018 conf: replace RHEL_KERNEL_VERSION with RHEL_RELEASE_NO

LU-6018 conf: replace RHEL_KERNEL_VERSION with RHEL_RELEASE_NO

No longer we use kernel version to detect kernel when we
compile ofed compat-rdma. We are using RHEL_RELEASE_NO

Signed-off-by: Minh Diep <minh.diep@intel.com>
Change-Id: Iab9a316570b61dfecf1c65c5da5e7af6a68601a5
Reviewed-on: http://review.whamcloud.com/13033
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>