ARC: Cache: Allways check D$ status before entire/line ops

ARC: Cache: Allways check D$ status before entire/line ops

As we are planning to get rid of dozens of ifdef's in cache.c we
would better check D$ status before each entire/line operation
then check CONFIG_SYS_DCACHE_OFF config option.

This makes the code cleaner as well as D$ entire/line functions
remain functional even if we enable or disable D$ in run-time.

As we need to check status before *each* function execution and we
call D$ entire/line functions from different places we add
this check directly into D$ entire/line functions instead of
their callers to avoid code duplication.

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