Place clock type values in the correct positon

Signed-off-by: Dale P. Smith  <dalepsmith@gmail.com>
Allow received GET management messages to have bodies

You'd probably expect the body of GET messages to be empty, but
interpretation #29 in
http://standards.ieee.org/findstds/interps/1588-2008.html implies
otherwise. With this change, ptp4l will respond to GETs containing
either an empty dataField or a dataField whose length matches the
managementId. If present, the contents of the dataField are ignored.

Signed-off-by: Geoff Salmon <gsalmon@se-instruments.com>