V4L/DVB (7042): xc5000: Tuner analog support

From Zhang: This an updated patch that adds analog support for
the xc5000 tuner driver. it was tested on a Pinnacle PCTV HD 800i
card (patches to follow).

Patch commited as-is, cleanup to follow ... Steve.

Signed-off-by: Chaogui Zhang <czhang1974@gmail.com>
Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>