bugfix: LlcProtocolTag: the setProtocol() and getProtocol() functions was asymmetric

The getProtocol() doesn't return the value prot of previous used setProtocol(prot)

Author: ZoltanBojthe

src/inet/linklayer/ieee80211/llc/LlcProtocolTag.msg

@@ -38,5 +38,5 @@ class LlcProtocolTag extends TagBase
 
 cplusplus(LlcProtocolTag) {{
     virtual const Protocol *getProtocol() const { return llc.findProtocol(getProtocolId()); }
-    virtual void setProtocol(const Protocol *protocol) { setProtocolId(static_cast<LlcProtocolId>(protocol->getId())); }
+    virtual void setProtocol(const Protocol *protocol) { setProtocolId(llc.getProtocolNumber(protocol)); }
 }}