hv: implement PCI bus scan function

- It starts from scaning bus 0 and scan other buses only if it is referred
  as a Secondary Bus by a PCI-to-PCI bridge.
- Skip to next device if function 0 is not implemented.
- Don't enumerate function 1-7 if a device is not a multi-function device.

Tracked-On: #1568
Signed-off-by: dongshen <dongsheng.x.zhang@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Reviewed-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>

hypervisor/include/dm/pci.h

@@ -142,6 +142,8 @@ enum pci_bar_type {
 	PCIBAR_MEM64,
 };
 
+typedef void (*pci_enumeration_cb)(uint16_t pbdf, void *data);
+
 static inline uint32_t pci_bar_offset(uint32_t idx)
 {
 	return PCIR_BARS + (idx << 2U);
@@ -160,4 +162,6 @@ static inline bool pci_bar_access(uint32_t offset)
 uint32_t pci_pdev_read_cfg(union pci_bdf bdf, uint32_t offset, uint32_t bytes);
 void pci_pdev_write_cfg(union pci_bdf bdf, uint32_t offset, uint32_t bytes, uint32_t val);
 
+void pci_scan_bus(pci_enumeration_cb cb, void *data);
+
 #endif /* PCI_H_ */