EX-4822 build: fix ubuntu mofed dkms

EX-4822 build: fix ubuntu mofed dkms

MOFED is always installed via dkms.
The path /usr/src/ofa_kernel hasn't changed
after MOFED 5.5 so we will use the
new way to detect in non-ubuntu only

Test-Parameters: trivial

Change-Id: Ie76b90f61449aaa880c44c8184691711f4ccfb19
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/46536
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>