sunxi: update cpu_sunxi_ncat2.h

sunxi: update cpu_sunxi_ncat2.h

The cpu_sunxi_ncat2.h header file contains addresses of some peripherals
that are needed for the SPL, for chips that belong to the "NCAT2"
generation.
The Allwinner A523 is a member of this group, but a few addresses
differ, and we need a few more addresses, for playing with the core
reset, for instance.

Add the new addresses needed for the A523 and guard existing definitions
that conflict with that new chip.

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