media: pci: remove unnecessary (void*) conversions

No need cast (void*) to (struct dst_state *),
(struct cx18_stream *), (struct saa7164_port *)
or (struct budget *).

Signed-off-by: Su Hui <suhui@nfschina.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>