tty: add ASYNC_SPLIT_TERMIOS to deprecation mask

Callout devices are long-gone, but the ASYNC_SPLIT_TERMIOS flag was
never added to the deprecation mask.

Add it so that a warning is printed if it is ever used.

Fixes: 8a8ae62f ("tty: warn on deprecated serial flags")
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407095208.31838-7-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/uapi/linux/tty_flags.h

@@ -73,8 +73,8 @@
 #define ASYNC_MAGIC_MULTIPLIER	(1U << ASYNCB_MAGIC_MULTIPLIER)
 
 #define ASYNC_FLAGS		((1U << (ASYNCB_LAST_USER + 1)) - 1)
-#define ASYNC_DEPRECATED	(ASYNC_SESSION_LOCKOUT | ASYNC_PGRP_LOCKOUT | \
-		ASYNC_CALLOUT_NOHUP | ASYNC_AUTOPROBE)
+#define ASYNC_DEPRECATED	(ASYNC_SPLIT_TERMIOS | ASYNC_SESSION_LOCKOUT | \
+		ASYNC_PGRP_LOCKOUT | ASYNC_CALLOUT_NOHUP | ASYNC_AUTOPROBE)
 #define ASYNC_USR_MASK		(ASYNC_SPD_MASK|ASYNC_CALLOUT_NOHUP| \
 		ASYNC_LOW_LATENCY)
 #define ASYNC_SPD_CUST		(ASYNC_SPD_HI|ASYNC_SPD_VHI)