Unlike other ATH11K PCIe devices which are enumerated by APSS
processor (Application Processor SubSystem), WCN6750 gets
enumerated by the WPSS Q6 processor (Wireless Processor SubSystem);
In simple terms, though WCN6750 is PCIe device, it is not attached
to the APSS processor, APSS will not know of such a device being
present in the system and therefore WCN6750 will be registered as
a platform device to the kernel core like other supported AHB
devices.

WCN6750 needs both AHB and PCI APIs for it's operation, it uses
AHB APIs for device probe/boot and PCI APIs for device setup and
register accesses. Because of this nature, it is referred as a
hybrid bus device.

Refactor PCI code to support hybrid bus devices like WCN6750.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1
Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.5.0.1-01100-QCAHKSWPL_SILICONZ-1
Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-00192-QCAHKSWPL_SILICONZ-1
Signed-off-by: Manikanta Pubbisetty <quic_mpubbise@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220328055714.6449-3-quic_mpubbise@quicinc.com