staging: rtl8188eu: use ETH_ALEN

Use ETH_ALEN instead of hard coded array size.
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20200929062847.23985-4-straube.linux@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/include/rtw_security.h

@@ -82,7 +82,7 @@ union Keytype {
 
 struct rt_pmkid_list {
 	u8	bUsed;
-	u8	bssid[6];
+	u8	bssid[ETH_ALEN];
 	u8	PMKID[16];
 	u8	SsidBuf[33];
 	u8	*ssid_octet;