ath79: fix 5GHz External Antenna A GPIO for BSAP-1840
Each ath9k device only has 10 gpios. ath9k-0 gpio number range is
502-511, and ath9k-1 gpio number range is 492-501. So "5GHz External
Antenna A" gpio line number should be 492 instead of 489.
Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/15784
Signed-off-by: Robert Marko <[email protected]>