cfg80211: reg: centralize freeing ignored requests

Instead of having a lot of places that free ignored requests
and then return REG_REQ_OK, make reg_process_hint() process
REG_REQ_IGNORE by freeing the request, and let functions it
calls return that instead of freeing.

This also fixes a leak when a second (different) country IE
hint was ignored.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>