arm64: dts: meson-g12-common: Use the G12A UART compatible string

arm64: dts: meson-g12-common: Use the G12A UART compatible string

Switch meson-12-common.dtsi to use the Meson G12A specific UART
compatible string. This enables the "divide XTAL by 2" divider which
improves support for UART attached Bluetooth modules (for example
RTL8822CS) running at a baud rate of 1500000. Without dividing XTAL
(24MHz) by 2 a baud rate of 1500000 cannot be generated cleanly and the
resulting jitter breaks communication with the module.

Tested-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230307222651.2106615-4-martin.blumenstingl@googlemail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>