tty: serial: remove obsolete config SERIAL_SAMSUNG_UARTS_4

Commit 1ea35b35

 ("ARM: s3c: remove s3c24xx specific hacks"), allows
simplifying the whole config logic for SERIAL_SAMSUNG_UARTS, and did this
config simplification. However, it misses that SERIAL_SAMSUNG_UARTS_4's
effect was just to control SERIAL_SAMSUNG_UARTS, and with the commit's
change, the config SERIAL_SAMSUNG_UARTS_4 has no remaining effect and can
be deleted.

Remove this obsolete config SERIAL_SAMSUNG_UARTS_4.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230317071538.29366-1-lukas.bulwahn@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>