ath11k: fix IRQ affinity warning on shutdown

Make sure to clear the IRQ affinity hint also on shutdown to avoid
triggering a WARN_ON_ONCE() in __free_irq() when stopping MHI while
using a single MSI vector.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3

Fixes: e94b0749 ("ath11k: Set IRQ affinity to CPU0 in case of one MSI vector")
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220523143258.24818-1-johan+linaro@kernel.org