pc80/mc146818rtc.h: Has X86 specific inlines without guards

PC80 header components are winding up in ARM builds with static inline
X86 specific code.

Change-Id: Ib23e70a34c478dc099b84b59a5234539cc2482e3
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6101
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <gaumless@gmail.com>
diff --git a/src/include/pc80/i8254.h b/src/include/pc80/i8254.h
index f4f0dca..964cc97 100644
--- a/src/include/pc80/i8254.h
+++ b/src/include/pc80/i8254.h
@@ -59,4 +59,5 @@
 #define PPCB_T2GATE     0x01    /* Bit 0 */
 
 void setup_i8254(void);
-#endif
+
+#endif /* PC80_I8254_H */