feat(allwinner): add function to detect H616 die variant

feat(allwinner): add function to detect H616 die variant

Allwinner provides a number of SoCs that use the same die as the H616.
Some of those chips apparently use a slight variation of that die, that
differs in the way the CPU cores' power and reset controls are handled.
This die variation can be detected by reading the SRAM version register.

Provide a predicate function that returns false if that die variant is
used. Since the CPU power control code is shared for all supported SoCs,
we provide an instance of this function for each SoC, as a static
inline, and return true on all other SoCs. This allows to always use
this function, and still let the compiler optimise away the unneeded
branch for those older SoCs.

This function is unused for now, but is needed in the next patch.

Change-Id: I49e014b895b7e2f55b4e7dc2b3d8aa31cee711b5
Signed-off-by: Andre Przywara <andre.przywara@arm.com>