Merge tag 'u-boot-amlogic-20200428' of https://gitlab.denx.de/u-boot/custodians/u-boot-amlogic

- fix sd-emmc controller A init on G12A/G12B/SM1 SoCs
- add GXBB USB PHY driver
- enable access to SPI NOR Flash on VIM2 and VIM3/VIM3L boards
- fix USB PHYs Power-Up on on VIM3/VIM3L boards