target-m68k: Clean includes

config.h was missing in cpu.h.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
diff --git a/target-m68k/cpu.h b/target-m68k/cpu.h
index 0667f82..4cc3a35 100644
--- a/target-m68k/cpu.h
+++ b/target-m68k/cpu.h
@@ -24,6 +24,7 @@
 
 #define CPUState struct CPUM68KState
 
+#include "config.h"
 #include "qemu-common.h"
 #include "cpu-defs.h"