When pickup fails, inform the user and close down the channel nicely

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5282 43c1dc8c-776e-4df2-8ef1-6e829299be21
Fix skinny_codec_pref_remove (related to revision #5280)

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5283 43c1dc8c-776e-4df2-8ef1-6e829299be21