sunxi: prepare for sharing MACH_SUN8I_H3 config symbol

sunxi: prepare for sharing MACH_SUN8I_H3 config symbol

The Allwinner H5 is very close to the H3 SoC, but has ARMv8 cores.
To allow sharing the clocks, GPIO and driver code easily, create an
architecture agnostic MACH_SUNXI_H3_H5 Kconfig symbol.
Rename the existing symbol to MACH_SUNXI_H3_H5 where code is shared and
let it be selected by a new shared Kconfig option.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>