Disable all libv4l2 emulated formats with V4L2_DISABLE_CONVERSION.

We get several emulated formats enumerated as supported, e.g. RGB,
from libv4l2. These are too inefficient to use in any real world
use case vs. using videoconvert on the CPU with ORC, or glfilterbin
on the GPU. With this change only the natively supported formats
will be enumerated, same as:
v4l2-ctl --list-formats-ext

Change-Id: If56c9f2f7be122e42f7a9729d60450eb8a127fb8
1 file changed