dpaa2-switch: rename dpaa2_switch_acl_tbl into filter_block

Until now, shared filter blocks were implemented only by ACL tables
shared between ports. Going forward, when the mirroring support will be
added, this will not be true anymore.

Rename the dpaa2_switch_acl_tbl into dpaa2_switch_filter_block so that
we make it clear that the structure is used not only for filters that
use the ACL table but will be used for all the filters that are added in
a block.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>