ARC: CACHE: add support for SL$ disable

Since version 3.0 ARC HS supports SL$ (L2 system level cache)
disable. So add support for SL$ disable/enable to code.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
2 files changed