Having two separate if ladders gets increasingly hard to maintain. Put
them together.

v2: Rebase
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180926133414.22073-1-jani.nikula@intel.com