V4L/DVB (7186): tda10086: make the 22kHz tone for DISEQC a config option

Some cards need the diseqc signal modulated, while some just need
the envelope to control the LNB supply.

This fixes Bug 9887


Signed-off-by: Hartmut Hackmann <hartmut.hackmann@t-online.de>
Acked-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>