tty: synclink_cs: Use bitwise instead of arithmetic operator for flags

This silences the following coccinelle warning:
drivers/s390/char/tape_34xx.c:360:38-39: WARNING: sum of probable bitmasks, consider |

we will try to make code cleaner
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Link: https://lore.kernel.org/r/1647846757-946-1-git-send-email-baihaowen@meizu.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/pcmcia/synclink_cs.c

@@ -922,7 +922,7 @@ static void rx_ready_async(MGSLPC_INFO *info, int tcd)
 		// BIT7:parity error
 		// BIT6:framing error
 
-		if (status & (BIT7 + BIT6)) {
+		if (status & (BIT7 | BIT6)) {
 			if (status & BIT7)
 				icount->parity++;
 			else