fixes posible refcount issue in sccp_wrapper_recvdigit_end

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4535 43c1dc8c-776e-4df2-8ef1-6e829299be21
fixes warnings

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4536 43c1dc8c-776e-4df2-8ef1-6e829299be21