staging: vt6655: add new stucture struct vnt_phy_field for rts/cts/data structures

This will replace bySignalField*, byServiceField* and wTransmitLength_b
members of these strutures, these are removed in the last patch.

The len member is of little endian type.

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