ath5k: Preserve pcicfg bits during attach

* During attach preserve pcicfg bits when enabling pci core
   sw retry fix.
Signed-off-by: NNick Kossifidis <mickflemm@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/attach.c

@@ -261,7 +261,7 @@ struct ath5k_hw *ath5k_hw_attach(struct ath5k_softc *sc, u8 mac_version)
 
 	/* Enable pci core retry fix on Hainan (5213A) and later chips */
 	if (srev >= AR5K_SREV_AR5213A)
-		ath5k_hw_reg_write(ah, AR5K_PCICFG_RETRY_FIX, AR5K_PCICFG);
+		AR5K_REG_ENABLE_BITS(ah, AR5K_PCICFG, AR5K_PCICFG_RETRY_FIX);
 
 	/*
 	 * Get card capabilities, calibration values etc