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

In the Linux kernel, the following vulnerability has been resolved: 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.