ramips: mt76x8 add support for RTC class/drivers

This commit adds support for RTC class/drivers to the mt76x8 target.

Signed-off-by: Xiaobo Liu <[email protected]>

target/linux/ramips/mt76x8/config-5.15

@@ -162,6 +162,7 @@ CONFIG_REGMAP_MMIO=y
 CONFIG_REGULATOR=y
 CONFIG_REGULATOR_FIXED_VOLTAGE=y
 CONFIG_RESET_CONTROLLER=y
+CONFIG_RTC_CLASS=y
 CONFIG_SERIAL_8250_NR_UARTS=3
 CONFIG_SERIAL_8250_RUNTIME_UARTS=3
 CONFIG_SERIAL_MCTRL_GPIO=y