V4L/DVB: tvp7002: fix compilation breakage when advanced debug is enabled

> On Mon, 22 Feb 2010 08:21:44 -0800 Randy Dunlap wrote:
> drivers/media/video/tvp7002.c:896: error: 'struct tvp7002' has no member named 'registers'
>
> so where are these registers??

Hmm, that code is a remnant from older revisions of this driver. Unfortunately,
when I compiled this driver before creating my pull request I forgot to turn on
the CONFIG_VIDEO_ADV_DEBUG option and so I never saw it.

Also fixed the g_register function: it never returned a register
value in the original code.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>