Fix: Make sccp_session_removeDevice return the device that was removed from the session, so that we can use it for some other action. Use sccp_session_removeDevice during crossoversession handling (Which includes locking the session during the procedure.). (Minor Issue reported by Pavel).

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5661 43c1dc8c-776e-4df2-8ef1-6e829299be21