tools/sdiodevs2h.awk: introduce palias

Some of the defined names are not the direct 1:1 mapping with vendor
and device names used by Linux device drivers.
Introduce a p(roduct)alias so we can map the one device entry I came
across without much extra hassle and generate a name device drivers
know about:
palias BROADCOM_CYPRESS_43439 CYPRESS_43439

Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D46455