net: dsa: microchip: Don't free uninitialized ksz_irq

net: dsa: microchip: Don't free uninitialized ksz_irq

If something goes wrong at setup, ksz_irq_free() can be called on
uninitialized ksz_irq (for example when ksz_ptp_irq_setup() fails). It
leads to freeing uninitialized IRQ numbers and/or domains.

Use dsa_switch_for_each_user_port_continue_reverse() in the error path
to iterate only over the fully initialized ports.

Cc: stable@vger.kernel.org
Fixes: cc13ab18b201 ("net: dsa: microchip: ptp: enable interrupt for timestamping")
Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
Link: https://patch.msgid.link/20251120-ksz-fix-v6-3-891f80ae7f8f@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>