Refactor ksz8_fdb_dump() to address potential issues:
- Limit the number of iterations to avoid endless loops.
- Handle error codes returned by ksz8_r_dyn_mac_table(), with
an exception for -ENXIO when no more dynamic entries are detected.
Reviewed-by: Vladimir Oltean <olteanv@xxxxxxxxx>
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>