net: airoha: enable RX_DONE interrupt for RX queue 31

RX queue 31 has always been allocated and filled by airoha_qdma_init_rx()
since RX_DONE_INT_MASK spans queues 0-31, but none of the RX_IRQ*
_BANK_PIN_MASK values covered BIT(31). As a consequence the RX_DONE
interrupt for queue 31 was never enabled, airoha_qdma_rx_process() never
ran on that queue and its buffers were never reaped.

Route RX queue 31's RX_DONE interrupt to IRQ bank 1 so that the queue
is drained and its buffers returned to the page pool.

Fixes: f252493e1835 ("net: airoha: Enable multiple IRQ lines support in airoha_eth driver.")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260830-airoha-rxdone-rxq31-v1-1-830a91503f2f@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>