airo: 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/b3c0f74f5b6e6bff9f1609b310319b6fdd9ee205.1605896059.git.gustavoars@kernel.org

drivers/net/wireless/cisco/airo.c

@@ -7065,6 +7065,7 @@ static int airo_set_power(struct net_device *dev,
 			local->config.rmode &= ~RXMODE_MASK;
 			local->config.rmode |= RXMODE_BC_MC_ADDR;
 			set_bit (FLAG_COMMIT, &local->flags);
+			break;
 		case IW_POWER_ON:
 			/* This is broken, fixme ;-) */
 			break;