ath5k: Preserve pcicfg bits during attach

* During attach preserve pcicfg bits when enabling pci core
   sw retry fix.

Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath5k/attach.c b/drivers/net/wireless/ath/ath5k/attach.c
index 238eeb7..65d438b 100644
--- a/drivers/net/wireless/ath/ath5k/attach.c
+++ b/drivers/net/wireless/ath/ath5k/attach.c
@@ -261,7 +261,7 @@
 
 	/* 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