Various improvements to Snapdragon support:
* Bumped up the pagetable size to handle newer SoCs with much more RAM
* Made memory map parsing more robust, fixing chainloading on
SM8550/SM8650
* Populate fdt_addr_r with U-Boot's FDT by default, and set $loadaddr to
prevent
crashes with some commands which expect it
* Added initial support for SC7280/QCM6490 and the new RB3 Gen 2 board
* Add debug config fragments to enable debug UART on some SoCs.
* Enable RPMh regulators on SM8550/SM8650
* Map the cmd-db memory explicitly since it may not be in the memory map
CI: https://source.denx.de/u-boot/custodians/u-boot-snapdragon/-/pipelines/22255