ARC: add macro to get CPU id
ARCNUM [15:8] field in ARC_AUX_IDENTITY register allows us to
uniquely identify each core in a multi-core system.
I.e. with help of this macro each core may get its index in SMP system.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>