cfg80211: remove REGDOM_SET_BY_INIT

This is not used as we can always just assume the first
regulatory domain set will _always_ be a static regulatory
domain. REGDOM_SET_BY_CORE will be the first request from
cfg80211 for a regdomain and that then populates the first
regulatory request.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>