DVB: tda10086: make the 22kHz tone for DISEQC a config option

(backported from commit ea75baf4)

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>
Cc: Hermann Pitton <hermann-pitton@arcor.de>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>