Merge patch series "MIPS: Boston: Various enhancements"

Merge patch series "MIPS: Boston: Various enhancements"

Jiaxun Yang <jiaxun.yang@flygoat.com> says:

This is a huge series which promoted MIPS/Boston target into a
usable state, with fixes to drivers and general framework issues
I found in this process.

I also converted the target to OF_UPSTREAM.

This target is covered by QEMU, to test on QEMU:
```
make boston64r6el_defconfig
make
qemu-system-mips64el -M boston -cpu I6500 -bios ./u-boot.bin -nographic
```

Link: https://lore.kernel.org/r/20240517-boston-v3-0-1ea7d23f4a1d@flygoat.com