rtspsrc: Fix critical while serializing timeout element message
The "cause" field is a C enum, not a GEnumValue.
gst_structure_to_string()
yields this critical:
gst_value_serialize: assertion 'G_IS_VALUE (value)' failed
C enums are supposed to be stuffed as integers, not as G_TYPE_ENUM
.
Edited by Nirbheek Chauhan