staging: vt6556: vnt_start Fix missing call to vnt_key_init_table.

The key table is not intialized correctly without this call.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Cc: <stable@vger.kernel.org> # v3.17+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>