ARC: enable barriers for HS

As we start to use data memory barriers in SMP scheduler code
explicitly (not only internaly in the atomics implementation)
let's enable barriers for ARC HS.

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