wifi: ath12k: fix firmware assert during reboot with hardware grouping

wifi: ath12k: fix firmware assert during reboot with hardware grouping

At present, during PCI shutdown, the power down is only executed for a
single device. However, when operating in a group, all devices need to be
powered down simultaneously. Failure to do so will result in a firmware
assertion.

Hence, introduce a new ath12k_pci_hw_group_power_down() and call it during
power down. This will ensure that all partner devices are properly powered
down.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1
Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250408-fix_reboot_issues_with_hw_grouping-v4-5-95e7bf048595@oss.qualcomm.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>