Merge branch 'master' of https://source.denx.de/u-boot/custodians/u-boot-sunxi

One fix makes the reboot more robust on some older board, another one
stabilises the initial clock setup on the A10/A20.
Two patches make sure our DRAM init does not actually change the content
of the DRAM array, which allows to use DRAM for Linux' pstore
functionality.
We get SPI support for U-Boot proper for one more SoC, that patch was
lingering around for a while, and should not affect other SoCs, so I am
merging this now.
As an added bonus, we get the defconfig file for a new board, the DT was
already synced from the kernel tree.

The CI looked happy with changes, and I tested them on five different
boards with different SoCs.