V4L/DVB (8985): S2API: Added dvb frontend changes to support a newer tuning API

V4L/DVB (8985): S2API: Added dvb frontend changes to support a newer tuning API

This is an experimental patch to add a new tuning mechanism for
dvb frontends. Rather than passing fixed structures across the
user/kernel boundary, which need to be revised for each new modulation
type (or feature the kernel developers want to add), this implements
a simpler message based approach, allowing fe commands to be broken
down into a series of small fixed size transactions, presented
in an array.

The goal is to avoid changing the user/kernel ABI in the future, by
simply creating new frontend commands (and sequencies of commands) that
help us add support for brand new demodulator, delivery system or
statistics related commmands.

known issues:
checkpatch voilations
feedback from various developers yet to be implemented, relating
to namespace conventions, variable length array passing conventions,
and generally some optimization.

This patch should support all existing tuning mechanisms through the
new API, as well as adding 8PSK, DVB-S2 NBC-QPSK and ISDB-T API support.

For testing and exercise purposes, see the latest tune.c tool
available from http://www.steventoth.net/linux/s2

Signed-off-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>