wifi: ath11k: fix suspend use-after-free after probe failure

wifi: ath11k: fix suspend use-after-free after probe failure

Make sure to deregister the PM notifier to avoid a use-after-free on
suspend in case core initialisation fails (e.g. due to missing
firmware).

Tested-on: WCN6855 hw2.0 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.41

Fixes: 32d93b51bc7e ("wifi: ath11k: choose default PM policy for hibernation")
Reported-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Closes: https://lore.kernel.org/all/d0cd065c-1cd1-4e56-8c57-60777b1f3664@oss.qualcomm.com/
Cc: Baochen Qiang <quic_bqiang@quicinc.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://patch.msgid.link/20250624082022.15469-1-johan+linaro@kernel.org
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>