Fix potential out-of-bound array access

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5235 43c1dc8c-776e-4df2-8ef1-6e829299be21
Fix potential null pointer dereference

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5236 43c1dc8c-776e-4df2-8ef1-6e829299be21