Merge tag 'u-boot-amlogic-20200406' of https://gitlab.denx.de/u-boot/custodians/u-boot-amlogic into next

- clk: meson-g12a: missing break
- sync all Amlogic DT from Linux v5.6-rc2
- MMC clock fixups
- add support for Libre Computer AML-S905D-PC and AML-S912-PC