Add support for Amlogic Meson GXM SoC with :
- Revert old platform meson code
- Add T820 compatible
- Add platforms specific soft reset callback used in the meson specific devicetree code
- Move PLATFORM_POWER_ONLY to a Kconfig to be used only by the meson-gxm config
- Add devicetree variant for meson with code to power-on and soft reset the GPU cores, since the autopm HW is broken
- Add support for variant config file names
Add fixes for :
- kbase_gpuprobes for Linux 4.20+
- reservation_object_reserve_shared for Linux 5.0+