ARC: boost default stacks in case of 64BIT

Increase stacks required for ARCv3 64-bit CI to pass.
The CMSIS stacks are for programs in samples/portability

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