staging: vt6656: rxtx.h always pack BEACON_BUFFER/TX_BUFFER

All structure members of BEACON_BUFFER/TX_BUFFER should be packed.

Only the first 4 members of these structures are live.

The forth member is referenced at run-time by packed structures.
typedef struct tagSTxBufHead
typedef struct tagSTxShortBufHead
in desc.h

If these structures are not packed the alignment of these members
will be wrong.

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