net: dsa: microchip: ksz8: Refactor ksz8_fdb_dump()

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@gmail.com>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Link: https://lore.kernel.org/r/20240403125039.3414824-4-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>