serial: ralink: adds Mediatek MT7620 serial

Add the config symbol for Mediatek MT7620 SoC to the SERIAL_8250_RT288X
dependencies.
Signed-off-by: NJohn Crispin <blogic@openwrt.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/Kconfig

@@ -293,7 +293,7 @@ config SERIAL_8250_EM
 
 config SERIAL_8250_RT288X
 	bool "Ralink RT288x/RT305x/RT3662/RT3883 serial port support"
-	depends on SERIAL_8250 && (SOC_RT288X || SOC_RT305X || SOC_RT3883)
+	depends on SERIAL_8250 && (SOC_RT288X || SOC_RT305X || SOC_RT3883 || SOC_MT7620)
 	help
 	  If you have a Ralink RT288x/RT305x SoC based board and want to use the
 	  serial port, say Y to this option. The driver can handle up to 2 serial