net: airoha: npu: Read NPU wlan interrupt lines from the DTS

net: airoha: npu: Read NPU wlan interrupt lines from the DTS

Read all NPU wlan IRQ lines from the NPU device-tree node.
NPU module fires wlan irq lines when the traffic to/from the WiFi NIC is
not hw accelerated (these interrupts will be consumed by the MT76 driver
in subsequent patches).
This is a preliminary patch to enable wlan flowtable offload for EN7581
SoC.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250811-airoha-en7581-wlan-offlaod-v7-5-58823603bb4e@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>