staging: vt6655: rxtx.c create function to return __le16 wTimeStampOff

wTimeStampOff always needs to be endian corrected.

Create vnt_time_stamp_off to return this value.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>