ANDROID: usb: host: fix slab-out-of-bounds in xhci_vendor_get_ops

slab-out-of-bounds happens if the xhci platform drivers don't define
the extra_priv_size in their xhci_driver_overrides structure. Move
xhci_vendor_ops structure to xhci main structure to avoid
extra_priv_size affacts xhci_vendor_get_ops which causes the
slab-out-of-bounds error.

Bug: 194461020
Test: build and boot pass
Change-Id: Id17fdfbfd3e8edcc89a05c9c2f553ffab494215e
Signed-off-by: Howard Yen <howardyen@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>