ath5k: add a new bus op for reading the mac address

On AHB, the calibration data usually does not contain a valid MAC address,
the correct MAC address is stored in the board config.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --cc drivers/net/wireless/ath/ath5k/ahb.c
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/ath5k.h
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/base.c
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/eeprom.c
Simple merge

diff --cc drivers/net/wireless/ath/ath5k/pci.c
Simple merge