MFC r353528-r353529

r353528:
arm64: allwinner: Add Allwinner H6 Support

This adds support for H6 SoC.
Add a CCU driver for H6 that support all PLLs and most of the clocks
that we are intersted in for now (i2c, mmc, usb, etc ...)

r353529:
arm64: allwinner: Add H6 GPIO/Pinctrl driver

This adds support for Allwinner H6 GPIO and pinctrl driver for
both the main pinctrl unit and the 'r_' one.