arm64: dts: allwinner: h700: Add RG35XX 2024 DTS

The base model RG35XX (2024) is a handheld gaming device based on an
Allwinner H700 chip.

The H700 is a H616 variant (4x ARM Cortex-A53 cores @ 1.5Ghz with Mali G31
GPU) which exposes RGB LCD and NMI pins.

Device features:
- Allwinner H700 @ 1.5GHz
- 1GB LPDDR4 DRAM
- X-Powers AXP717 PMIC
- 3.5" 640x480 RGB LCD
- Two microSD slots
- Mini-HDMI out
- GPIO keypad
- 3.5mm headphone jack
- USB-C charging port

Enabled in this DTS:
- AXP717 PMIC with RSB serial interface, regulators and NMI interrupt
controller
- Power LED (charge LED on device controlled directly by PMIC)
- Serial UART (accessible from headers on the board)
- First SD slot (SD2 appears to have a GPIO-switched regulator for 1.8v
low-voltage signalling, this is not yet modeled. Enablement with a
switched regulator will be confirmed and posted in a follow-up patch).

Signed-off-by: Ryan Walklin <ryan@testtoast.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lore.kernel.org/r/20240427110225.727472-6-ryan@testtoast.com
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>