cfg80211: declare MODULE_FIRMWARE for regulatory.db

Add MODULE_FIRMWARE declarations for regulatory.db and
regulatory.db.p7s such that userspace tooling can discover and include
these files.

Cc: stable@vger.kernel.org
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Link: https://lore.kernel.org/r/20220414125004.267819-1-dimitri.ledkov@canonical.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>