V4L/DVB (9443): Bug: Bandwidth calculation

Bug #1: The 5 tap equaliser is set to correct simple perturbations
like reflections on the IF cable for DVB-S. In the case of DVB-S2
a more powerful equalizer is used to correct the filter group delay
allowing the bandwidth to be reduced by a factor of 1/3

Bug #2: The ZIF tuner takes badwidth to be set in Hz

Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>