Merge https://gitlab.denx.de/u-boot/custodians/u-boot-mpc85xx into next

- Add DM_SPI, DM_SPI_FLASH support for powerpc platforms
- Add DM_ETH support on P1010RDB, P1020RDB, P2020RDB
- Reduce number of WATCHDOG_RESET calls from flush_cache
- Remove some un-maintained powerpc platforms
- Add USB_STORAGE support in config