V4L/DVB (8477): v4l: remove obsolete audiochip.h

Converted the last users of audiochip.h to the v4l2-chip-ident.h header
and remove the now unused audiochip.h header.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>