usb: move definition of PCI_VENDOR_ID_SYNOPSYS to linux/pci_ids.h

Removed FIXME from usb/dwc3/dwc3-pci.c by moving definition of
PCI_VENDOR_ID_SYNOPSYS shared with usb/dwc2 to linux/pci_ids.h.

Signed-off-by: Joseph Kogut <joseph.kogut@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>