ath9k: add support for reading eeprom from platform data on PCI devices

Some embedded boards store platform data for connected PCIe AR92xx
chips in the system flash instead of a separate EEPROM chip.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/init.c b/drivers/net/wireless/ath/ath9k/init.c
index 498f621..e7764ce 100644
--- a/drivers/net/wireless/ath/ath9k/init.c
+++ b/drivers/net/wireless/ath/ath9k/init.c
@@ -530,6 +530,9 @@
 	ah->hw_version.subsysid = subsysid;
 	sc->sc_ah = ah;
 
+	if (!sc->dev->platform_data)
+		ah->ah_flags |= AH_USE_EEPROM;
+
 	common = ath9k_hw_common(ah);
 	common->ops = &ath9k_common_ops;
 	common->bus_ops = bus_ops;