V4L/DVB (5011): DVB: Remove unneeded void * casts in ttpci/av7110

The patch removes unneeded void * casts for the following (void *) pointers:
- struct file: private_data
- struct dvb_device: priv
- struct dvb_demux: priv
- struct dvb_adapter: priv
The patch also contains some whitespace and coding style cleanups in the
relevant areas.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>