staging: vt6656: Move vnt_get_frame_time and vnt_get_phy_field to rxtx

These functions are only used by rxtx so move them and their arrays
used with them abbreviating the function description.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Link: https://lore.kernel.org/r/2a4fd665-2fe1-f1ad-1e9a-1b01f698ea79@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>