ath6kl: Define __CHECK_ENDIAN__ for sparse

Make sparse check endianness with "make C=1".
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath6kl/Makefile

@@ -33,3 +33,5 @@ ath6kl-y += txrx.o
 ath6kl-y += wmi.o
 ath6kl-y += node.o
 ath6kl-y += sdio.o
+
+ccflags-y += -D__CHECK_ENDIAN__