videbox: Use MIN instead of CLAMP for uint
videbox: Use MIN instead of CLAMP for uint

an unsigned int is always positive.

CID #206207
CID #206208
CID #206209
CID #206210
CID #206211

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/583>

GStreamer/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good,GStreamer/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good