dpaa2-switch: reorganize dpaa2_switch_cls_flower_replace

Extract the necessary steps to offload a filter by using the ACL table
in a separate function - dpaa2_switch_cls_flower_replace_acl().
This is intended to help with the code readability when the mirroring
support is added.

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