sunxi: add Allwinner R528/T113 SoC support

sunxi: add Allwinner R528/T113 SoC support

This adds the remaining code bits to teach U-Boot about Allwinner's
newest SoC generation. This was introduced with the RISC-V based
Allwinner D1 SoC, which actually shares a die with the ARM cores versions
called R528 (BGA, without DRAM) and T113s (QFP, with embedded DRAM).

This adds the new Kconfig stanza, using the two newly introduced symbols
for the new SoC generation and pincontroller. It also adds the new symbols
to the relavent code places, to set all the hardcoded bits directly.

We need one DT override:
The ARM core version of the DT specifies the CPUX watchdog as
"reserved", which means it won't be recognised by U-Boot. Override this
in our generic sunxi-u-boot.dtsi, to let U-Boot pick up this watchdog,
so that the generic reset driver will work.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>