[PATCH] dvb: Remove unnecessary casts

Cleanup unnecessary (and undesirable) casts, demodulator_priv is already a
void*.  Suggestion from Andrew Morton

Signed-off-by: Manu Abraham <manu@kromtek.com>
Cc: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>