arch: arc: update ARConnect ICD select mask when new cpu come online

The ARConnect Inter-core Debug Unit (ICD) provides additional
debug assist features in multi-core scenarios. It's useful to halt
other cores when one core is halted.

Before we program ICD in master core(core 0) initial stage, add
all cores to mask. so we need to make sure other slave cores have
launched and in running mode before we enable ICD in master core.

If we launch master core first, then launch slave cores by master
core conditionally, in this scenario, it's not OK.

Let's update arc connect debug (ARConnect ICD) select mask
when new slave core come online by slave core self, instead of
use hardcoded select mask.

Signed-off-by: Watson Zeng <zhiwei@synopsys.com>