mac80211: ath9k: patch hw.c for gpio mask from dt

mac80211: ath9k: patch hw.c for gpio mask from dt

"qca,gpio-mask" used to be read between ath9k_hw_init() and
ath9k_init_queues(). After 12913c3c5658992985e13f4395dee86e5450154d
it is read in ath9k_of_init(), but it gets overwritten by
ath9k_gpio_cap_init() during the call of ath9k_hw_init(), and causes
https://github.com/openwrt/openwrt/issues/22340

If keeping the most of 12913c3c5658992985e13f4395dee86e5450154d,
ath9k_gpio_cap_init() could be patched to keep the existing non-zero
gpio mask (coming from device tree).

Tested on Netgear WNDR4500 v3:
[   22.558083] ath9k 0000:00:00.0: enabling device (0000 -> 0002)
[   22.569548] ath: phy1: Use overridden gpio mask 0xf6ff

Signed-off-by: Edward Chow <equu@openmail.cc>
Link: https://github.com/openwrt/openwrt/pull/22376
Signed-off-by: Robert Marko <robimarko@gmail.com>