opencv: remove gphoto2 via PACKAGECONFIG
opencv: remove gphoto2 via PACKAGECONFIG

Use the PACKAGECONFIG variable to remove ghoto2 from CMAKE, instead of
asserting our own CMAKE args. These two approaches should be
functionally equivalent, but PACKAGECONFIG has better upstream support.

Signed-off-by: Alex Stewart <04cdb2793e4fb0120cc30d1c823099f3862701f4@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt