videocrop: Fix icles tests.
Internally videcrop can call gst_video_crop_set_info() with NULL as in caps. Then critical messages are raised when the in caps are processed.
To fix this the in caps are checked, and if they are present, its capsfeature is extracted, otherwise, the previous raw caps detection remains as before.
Also the videocrop-test removes the format field in the structure because now its always passed.