usb_hcd_pci_probe — initialize PCI-based HCDs
USB Host Controller being probed
pci hotplug id connecting controller to HCD framework
!in_interrupt
Allocates basic PCI resources for this USB host controller, and then invokes the start method for the HCD associated with it through the hotplug entry's driver_data.
Store this function in the HCD's struct pci_driver as probe.