staging: greybus: remove timesync protocol support

While the timesync protocol was a great idea, it never ended up getting
implemented by any known hardware devices.  It's also a bit
"interesting" in how it ties into the platform controller.

So, just remove it for now.  It's not needed, no one uses it, and it's a
stumbling block in getting the greybus core code merged out of the
staging tree.  If anyone wants it in the future, reverting this patch is
a great place to start from.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alex Elder <elder@kernel.org>
Acked-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>