ath9k_hw: clean up hardware revision checks

- AR_SREV_5416_20_OR_LATER is always true, remove it
- AR_SREV_9280_20_OR_LATER is always true within eeprom_4k.c and eeprom_9287.c
- (AR_SREV_9271 || AR_SREV_9285) is always true in eeprom_4k.c

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/ar5008_phy.c b/drivers/net/wireless/ath/ath9k/ar5008_phy.c
index fac2c6d..b130c26 100644
--- a/drivers/net/wireless/ath/ath9k/ar5008_phy.c
+++ b/drivers/net/wireless/ath/ath9k/ar5008_phy.c
@@ -704,8 +704,7 @@
 		REG_WRITE(ah, AR_PCU_MISC_MODE2, val);
 	}
 
-	if (!AR_SREV_5416_20_OR_LATER(ah) ||
-	    AR_SREV_9280_20_OR_LATER(ah))
+	if (AR_SREV_9280_20_OR_LATER(ah))
 		return;
 	/*
 	 * Disable BB clock gating