V4L/DVB (5320): Filled in limiting values in tda827x.c

The parameters for minimum and maximum frequency were missing.
Also added mail addresses of the module authors.

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