feat(allwinner): add SMCCC SOCID support

The Allwinner SID device holds a 16-bit SoC identifier, which we already
use in our code.

Export this number through the generic SMCCC SOCID interface, to allow
an architectural identification of an Allwinner SoC. This enables access
to this information from non-secure world, simplifies generic drivers
(ACPI comes to mind), and gives easy and precise access to the SoC ID
from userland in OSes like Linux.

Change-Id: I91753046b2ae5408ca7bc0b864fcd97d24c8267c
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
2 files changed