V4L/DVB (8946): dib7000m: fix powerpc build error

The dib7000m_i2c_enumeration() function is not used by any public drivers,
however some prototype board use it. So '#if 0' for now, but don't remove it.

Thanks to Patrick Boettcher for clarifying this.

Cc: Patrick Boettcher <patrick.boettcher@desy.de>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>