gst/dccp/: CodeStyle improvements and minor fixes to the DCCP plugin.

gst/dccp/: CodeStyle improvements and minor fixes to the DCCP plugin.

Original commit message from CVS:
patch by: Leandro Melo de Sales <leandroal@gmail.com>
* gst/dccp/gstdccp.c:
* gst/dccp/gstdccp.h:
* gst/dccp/gstdccpclientsink.c:
* gst/dccp/gstdccpclientsink.h:
* gst/dccp/gstdccpclientsrc.c:
* gst/dccp/gstdccpserversink.c:
* gst/dccp/gstdccpserversrc.c:
* gst/dccp/gstdccpserversrc.h:
CodeStyle improvements and minor fixes to the DCCP plugin.
Fixes #553823.