Add support for dumping bcma/siba EROM tables to the console via a new
BHND_EROM_DUMP() method.

Dump the EROM tables to the coneole on mips/broadcom devices if bootverbose
is enabled; this functionality is primarily useful when debugging SoC EROM
parsing and device matching issues during early boot.

Reviewed by: mizhka
Approved by: adrian (mentor)
Sponsored by: Plausible Labs
Differential Revision: https://reviews.freebsd.org/D10122