ath5k: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of letting the code fall
through to the next case.

Link: https://github.com/KSPP/linux/issues/115Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/e127232621c4de340509047a11d98093958303c5.1605896059.git.gustavoars@kernel.org

drivers/net/wireless/ath/ath5k/mac80211-ops.c

@@ -433,6 +433,7 @@ ath5k_configure_filter(struct ieee80211_hw *hw, unsigned int changed_flags,
 	case NL80211_IFTYPE_STATION:
 		if (ah->assoc)
 			rfilt |= AR5K_RX_FILTER_BEACON;
+		break;
 	default:
 		break;
 	}