Using the right way to set the conference callerid (Thanks Marcello)

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4499 43c1dc8c-776e-4df2-8ef1-6e829299be21
Fix setting confstr

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@4500 43c1dc8c-776e-4df2-8ef1-6e829299be21