staging: vt6655: replace typedef struct tagDEVICE_TD_INFO and structure

Create struct vnt_td_info with members
mic_hdr
skb
buf
buf_dma
dwReqCount -> req_count
byFlags -> flags

In struct tagSTxDesc volatile is removed because it will generate a warning
(in any case this member is not) and renaming td_info.

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