arch: arc: enable the workaround of sleep only for SMP case in nsim

Because the issue of nsim, the sleep instruction doest not work
correctly when SMP is enabled. A workaround is introduced in commit
d56a12d9, this workaround should be enabled only for SMP case in
nsim.

For other cases, no need of this workaround.

This commit fixes #24276

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>