arc: cache: Support region operations, SLC, and entire cache operations

Added configurable support for L1 cache region operations,
which offers improved performance over line operations.
Added configurable support for SLC (system level cache).
Added support for entire cache operations: flush_all,
invd_all, flush_and_invd_all.

Reviewed-by: Aaron Komisar <aaron.komisar@tandemg.com>
Signed-off-by: Yanir Levin <ylevin@gsitechnology.com>