habanalabs: partly skip cache flush when in PMMU map flow

The PCI MMU cache is two layered. The upper layer, memcache, uses cache
lines, the bottom layer doesn't.

Hence, after PMMU map operation we have to invalidate memcache, to avoid
the situation where the new entry is already in the cache due to its
cache line being fully in the cache.

However, we do not have to invalidate the lower cache, and here we can
optimize, since cache invalidation is time consuming.

Signed-off-by: Yuri Nudelman <ynudelman@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>