LU-11541 build: Use correct kernel version for DKMS MLNX OFED.

LU-11541 build: Use correct kernel version for DKMS MLNX OFED.

Check for $O2IBPATHS/${LINUXRELEASE} before $O2IBPATHS/default.
The "default" link is only created on the first dkms build of OFED.
So if doing dkms build for another kernel it may not be pointing
to the correct kernel.

Test-Parameters: trivial

Signed-off-by: Ake Sandgren <ake.sandgren@hpc2n.umu.se>
Change-Id: If8054ee64cf8795ed0e3ee50a8ef9ced067059d7
Reviewed-on: https://review.whamcloud.com/33702
Tested-by: Jenkins
Reviewed-by: Nathaniel Clark <nclark@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>