ath: remove camel case from struct reg_dmn_pair_mapping

Fixes a checkpatch warning in ath10k:

drivers/net/wireless/ath/ath10k/mac.c:1636: WARNING: Avoid CamelCase: <regpair->regDmnEnum>

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath.h b/drivers/net/wireless/ath/ath.h
index b59cfbe..2f4f251 100644
--- a/drivers/net/wireless/ath/ath.h
+++ b/drivers/net/wireless/ath/ath.h
@@ -63,7 +63,7 @@
 };
 
 struct reg_dmn_pair_mapping {
-	u16 regDmnEnum;
+	u16 reg_domain;
 	u16 reg_5ghz_ctl;
 	u16 reg_2ghz_ctl;
 };