arm: mach-k3: Add support for device type detection

K3 SoCs are available in a number of device types such as
GP, HS-FS, EMU, etc. Like OMAP SoCs we can detect this at runtime
and should print this out as part of the SoC information line.
We add this as part of the common.c file as it will be used
to also modify our security state early in the device boot.

Signed-off-by: Andrew Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>