arm64: dts: allwinner: Add Tanix TX1 support

The Tanix TX1 is a tiny TV box with the Allwinner H313 SoC. The box
features no Ethernet or an SD card slot, which makes booting from it
somewhat interesting: Pressing the hidden FEL button and using a USB-A
to USB-A cable to upload code from a host PC is one way to run mainline.
The box features:
- Allwinner H313 SoC (4 * Arm Cortex-A53 cores)
- 1 or 2 GB DRAM
- 8 or 16 GB eMMC flash
- SCI S9082H WiFi chip
- HDMI port
- one USB 2.0 port
- 3.5mm AV port
- barrel plug 5V DC input via barrel plug

The devicetree covers most peripherals.
The eMMC did not work properly in HS200 speed mode, so this mode property
is omitted. HS-DDR seems to work fine.
The blue LED is connected to the same GPIO pin as the red LED, just
using the opposite polarity. Apparently there is no way of describing
this in DT, so the red LED is omitted.
Next to the FEL button is a hidden button, that can be pushed by using
something like a paperclip, through the ventilation vents of the case.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20240418104942.1556914-3-andre.przywara@arm.com
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>