The ccb_xflags enumeration was removed from FreeBSD/head in
r259397 (it contained the CAM_EXTLUN_VALID bit) and I added the
same type name with a different set of values back in r291716.

The old ccb_xflags enumeration still exists in FreeBSD stable/10.
Shift all of the new values by one bit to avoid compatibility
issues when merged to stable/10.

MFC after: 3 days
Sponsored by: Spectra Logic