ccconverter: fix framerate caps negotiation from non-cdp to cdp

We can only convert from non-cdp to cdp within the confines of valid cdp
framerates.  The existing caps negotiation code was allowing any
framerate to convert to a cdp output which is incorrect and would hit an
assertion later.

Part-of: <gstreamer/gst-plugins-bad!2388>
29 jobs for !2388 with backport-mr-2372-into-1.18-ccconverter-fix-input-caps-non-cdp-framerate in 25 minutes and 12 seconds (queued for 7 seconds)
merge request