LU-303 fix ofed download for bugfix releases

On the OFED download server both w.x.y and w.x.y.z releases are
stored in the w.x.y dir, so handle that properly for the w.x.y.z case.

Signed-off-by: Brian J. Murrell <brian@whamcloud.com>
Change-Id: I7e638571a31df215517d71e5997e7d0c6411bb90
Reviewed-on: http://review.whamcloud.com/864
Tested-by: Hudson
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Michael MacDonald <mjmac@whamcloud.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>