arm64: dts: meson: add support for the Smartlabs SML-5442TW

The Smartlabs SML-5442TW is based on the Amlogic P231 reference design
but with the following differences:

- The Yellow and Blue LEDs are available but disabled
- The Red and Green LEDs are used to signal off/on status
- uart_AO can be accessed after opening the case; soldered pins exist
- QCA9377 instead of the usual Ampak/Broadcom module

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20200510124129.31575-4-christianshewitt@gmail.com