net: ethernet: mtk_eth_soc: rely on mtk_pse_port definitions in mtk_flow_set_output_device

Similar to ethernet ports, rely on mtk_pse_port definitions for
pse wdma ports as well.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/b86bdb717e963e3246c1dec5f736c810703cf056.1694506814.git.lorenzo@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>