dt-bindings: arm: amlogic: add support for the Smartlabs SML-5442TW

dt-bindings: arm: amlogic: add support for the Smartlabs SML-5442TW

The SML-5442TW is an STB for O2 Czech IPTV/VOD and DVB-T/T2 based on the
Amlogic P231 reference design using the S905D chipset. Specs:

2GB DDR3 RAM
8GB eMMC storage
10/100 Base-T Ethernet
802.11 a/b/g/n/ac + BT 4.1 HS sdio wireless module (QCA9377)
2x single colour and 1x dual colour LEDs on the front panel
1x reset button on the front panel
HDMI 2.0 (4k@60p) video
Composite video + 2-channel audio output on 3.5mm jack
S/PDIF audio output
Single DVB-T/T2 tuner (AVL6762/MxL608)
2x USB 2.0 ports
1x micro SD card slot
UART pins (internal)

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200510124129.31575-3-christianshewitt@gmail.com