cfg80211: add function helpers to genregdb.awk

This has no functional change, this just lets us reuse
helpers at a later time.

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Acked-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>