ISDN: Eicon fix macro clash

The eicon header defined macros for byte, word, dword. Apart from that
not being a good idea in general, it did clash with the use of a parameter
called "word" in asm/signal.h. At some other place in the Eicon headers, 
there are also typedefs for these types, so the macros can simply go away.

drivers/isdn/eicon/pc.h

@@ -11,11 +11,6 @@
 #ifndef PC_H_INCLUDED
 #define PC_H_INCLUDED
 
-
-#define byte unsigned char
-#define word unsigned short
-#define dword unsigned long
-
 /*------------------------------------------------------------------*/
 /* buffer definition                                                */
 /*------------------------------------------------------------------*/