ARC: control shared (common) interrupts via IDU

Control shared interrupts enabling/disabling via IDU.
With that we can easily enable and disable them for all cores
in one place.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>