rtlwifi: rtl8821ae: phy: Mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtlwifi/rtl8821ae/phy.c

@@ -394,6 +394,7 @@ static void _rtl8812ae_phy_set_rfe_reg_24g(struct ieee80211_hw *hw)
 			rtl_set_bbreg(hw, RB_RFE_INV, BMASKRFEINV, 0x000);
 			break;
 		}
+		/* fall through */
 	case 0:
 	case 2:
 	default: