net: airoha: Add missing bits in airoha_qdma_cleanup_tx_queue()

net: airoha: Add missing bits in airoha_qdma_cleanup_tx_queue()

Similar to airoha_qdma_cleanup_rx_queue(), reset DMA TX descriptors in
airoha_qdma_cleanup_tx_queue routine. Moreover, reset TX_DMA_IDX to
TX_CPU_IDX to notify the NIC the QDMA TX ring is empty.

Fixes: 23020f0493270 ("net: airoha: Introduce ethernet support for EN7581 SoC")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260417-airoha_qdma_cleanup_tx_queue-fix-net-v4-2-e04bcc2c9642@kernel.org
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>