rtl8xxxu: add enumeration for channel bandwidth

There's a data field in H2C and C2H commands which is used to
carry channel bandwidth information. Add enumeration to make it
more descriptive in code.
Signed-off-by: Chris Chiu <chiu@endlessm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200320063833.1058-2-chiu@endlessm.com

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h

@@ -1133,6 +1133,15 @@ enum bt_mp_oper_opcode_8723b {
 	BT_MP_OP_ENABLE_CFO_TRACKING = 0x24,
 };
 
+enum rtl8xxxu_bw_mode {
+	RTL8XXXU_CHANNEL_WIDTH_20 = 0,
+	RTL8XXXU_CHANNEL_WIDTH_40 = 1,
+	RTL8XXXU_CHANNEL_WIDTH_80 = 2,
+	RTL8XXXU_CHANNEL_WIDTH_160 = 3,
+	RTL8XXXU_CHANNEL_WIDTH_80_80 = 4,
+	RTL8XXXU_CHANNEL_WIDTH_MAX = 5,
+};
+
 struct rtl8723bu_c2h {
 	u8 id;
 	u8 seq;

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c

@@ -4328,7 +4328,7 @@ void rtl8xxxu_gen2_update_rate_mask(struct rtl8xxxu_priv *priv,
 				    u32 ramask, u8 rateid, int sgi)
 {
 	struct h2c_cmd h2c;
-	u8 bw = 0;
+	u8 bw = RTL8XXXU_CHANNEL_WIDTH_20;
 
 	memset(&h2c, 0, sizeof(struct h2c_cmd));