usb: cdnsp: Fix for undefined reference to `usb_hcd_is_primary_hcd'

Patch fixes the following compilation error:

ld: drivers/usb/cdns3/host.o: in function `xhci_cdns3_suspend_quirk':
host.c:(.text+0x9): undefined reference to `usb_hcd_is_primary_hcd'

This reference to 'usb_hdc_is_primary_hcd' is from hcd_to_xhci(),
which is being built as a loadable module:

int xhci_cdns3_suspend_quirk(struct usb_hcd *hcd)
{
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);

Issue occurrd for following kernel configuration:
CONFIG_USB_GADGET=y
CONFIG_USB_SUPPORT=y
CONFIG_USB_COMMON=y
CONFIG_USB_ARCH_HAS_HCD=y
CONFIG_USB=m

CONFIG_USB_CDNS_SUPPORT=y
CONFIG_USB_CDNS_HOST=y
CONFIG_USB_CDNS3=m
CONFIG_USB_CDNS3_GADGET=y
CONFIG_USB_CDNS3_HOST=y

Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Peter Chen <peter.chen@nxp.com>