rv1103: enable RTL8812AU wifibroadcast on SD-card images

[kkbin505]

Problem

The rv1103_lite SD-card image does not provide the complete support required to use an RTL8812AU USB adapter with wifibroadcast:

• the writable overlay is not persisted across reboots;
• the USB2 OTG port may remain in device mode instead of host mode;
• rtl8812au-openipc does not build against the RV1103 Linux 5.10 kernel;
• the board does not select the RTL8812AU driver or wifibroadcast-ng;
• wifibroadcast always starts telemetry, including installations without a
  telemetry device.

This change adds an RV1103 SD-card kernel fragment with a persistent ext4 overlay, switches the RV1103 USB2 OTG PHY to host mode during boot, fixes the RTL8812AU Linux 5.10 build, and enables RTL8812AU and wifibroadcast for rv1103_lite.

Hardware tested on

Luckfox Pico Mini RV1103 Model A (SD card)
SC3336 3MP Camera
RTL8812au wifi usb card

Evidence

Before:

After:

Scope

• No kernel patches under general/package/all-patches/linux/ (those go to [OpenIPC/linux] https://github.com/OpenIPC/linux))
• No files specific to a single retail camera model (those go to OpenIPC/builder)
• No probing or bring-up tooling (that goes to OpenIPC/ipctool)
• Nothing under general/overlay/ or in a shared load_<vendor> script hardcodes a value specific to my board
• Package sources come from an OpenIPC repository, and any version bump keeps at least the specificity of the pin it replaces (a new package should pin a full 40-character SHA)
• No LD_PRELOAD, and no binaries that cannot be rebuilt from source
• New code is selected by a defconfig, so CI actually builds it

[flyrouter]

Custom configuration profiles are handled in the Builder repository.
Only basic patches with minimum configuration for running systems on each specific processor are accepted in the Firmware repository.