net: dsa: felix: Fix memory leak in felix_setup_mmio_filtering

net: dsa: felix: Fix memory leak in felix_setup_mmio_filtering

Avoid a memory leak if there is not a CPU port defined.

Fixes: 8d5f7954b7c8 ("net: dsa: felix: break at first CPU port during init and teardown")
Addresses-Coverity-ID: 1492897 ("Resource leak")
Addresses-Coverity-ID: 1492899 ("Resource leak")
Signed-off-by: José Expósito <[email protected]>
Reviewed-by: Vladimir Oltean <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>