cport: introduce cport packing functions
cport: introduce cport packing functions

Define and use functions to pack, unpack, and clear the CPort ID we
encode in messages sent for transmission over USB (as if for
UniPro).  These function identically to their Greybus counterparts.

Signed-off-by: Alex Elder <f429030cf5c0faf36fac3d102073b6e63a647baa@linaro.org>
Tested-by: Rui Miguel Silva <f529045c86d2c13bbdfc6f0cc7c0e057c243b006@linaro.org>
Reviewed-by: Rui Miguel Silva <f529045c86d2c13bbdfc6f0cc7c0e057c243b006@linaro.org>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@google.com>

projectara/gbsim,projectara/gbsim,gregkh/gbsim,gregkh/gbsim