V4L/DVB (3276): Added new diagnositics macros, convert msp3400 to the new macros.

- Added new v4l_err, v4l_warn, v4l_info and v4l_dbg macros to
v4l2-common.h for use in v4l-dvb i2c drivers. This ensures
a unique prefix for each device instance.
- At a later stage these macros may be reimplemented using the
device-generic macros from device.h.
- Converted the msp3400 driver to the new macros.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>