arm64: cputype info for Broadcom Vulcan

Add Broadcom Vulcan implementor ID and part ID in cputype.h. This is
to document the values.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>