tty: serial: meson: Added S4 SOC compatibility

Make UART driver compatible with S4 SOC UART.

Signed-off-by: Yu Tu <yu.tu@amlogic.com>
Link: https://lore.kernel.org/r/20220225073922.3947-7-yu.tu@amlogic.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>