Clarify the documentation to indicate that these
flags can only be used at the end, i.e. after them
a copy TFD (no flags set) is invalid.
Reported-by: NInbal Hacohen <inbal.hacohen@intel.com>
Reviewed-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>