Revert "wifi: ath9k: use devm for request_irq()"

This reverts commit 92da4ce8.

Felix pointed out that moving to devm for request_irq() can lead to a use after
free, and that avoiding that means having explicit frees that makes the devm
thing pretty pointless. So let's just revert the patch.

Link: https://lore.kernel.org/r/201f06b6-14f5-41bb-8897-49665cf14b66@nbd.name


Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://patch.msgid.link/20240808103758.11696-1-toke@toke.dk