The port number should always be correctly set. Do the same thing as the
switch above and use BUG() to signal that branch is not supposed to be
taken.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>