ARC: setup cpu possible mask according to possible-cpus dts property

[ Upstream commit a29a25275452c97fe35815f1eb9564f2a07a1965 ]

As we have option in u-boot to set CPU mask for running linux,
we want to pass information to kernel about CPU cores should
be brought up. So we patch kernel dtb in u-boot to set
possible-cpus property.

This also allows us to have correctly setuped MCIP debug mask.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>