V4L/DVB: radio: add support for SAA7706H Car Radio DSP

Initial support for the SAA7706H Car Radio DSP.

It is a I2C device and currently the mute control is supported.

When the device is unmuted it is brought out of reset and initiated using
the proposed intialisation sequence.

When muted the DSP is brought into reset state.

[akpm@linux-foundation.org: include delay.h]

Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Cc: Douglas Schilling Landgraf <dougsland@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>