tty: serial/crisv10.c: remove unnecessary null pointer check

The pointer tty is dereferened in line 3135, so it is not necessary to check
null again in line 3140.
Signed-off-by: NCong Ding <dinggnu@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/crisv10.c

@@ -3122,7 +3122,7 @@ static int rs_raw_write(struct tty_struct *tty,
 
 	/* first some sanity checks */
 
-	if (!tty || !info->xmit.buf)
+	if (!info->xmit.buf)
 		return 0;
 
 #ifdef SERIAL_DEBUG_DATA