V4L/DVB (5484): Set tda8290 to analog mode after init

Set tda8290 to analog mode after init, otherwise the tuner driver will 
not accept i.e. the standby command.

Signed-off-by: Hartmut Hackmann <hartmut.hackmann@t-online.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>