ensure USB config numbers always start from 1

Depending on which features (and thus USB configurations) are included
in the firmware, we need to re-define the ordering of the configuration
numbers, as the Atmel USBD driver simply assumes that configurations are
numbered 1..N without any gaps in the sequence.
diff --git a/firmware/src_simtrace/simtrace.h b/firmware/src_simtrace/simtrace.h
index df5f01b..725ef41 100644
--- a/firmware/src_simtrace/simtrace.h
+++ b/firmware/src_simtrace/simtrace.h
@@ -2,6 +2,7 @@
 #define SIMTRACE_H
 
 #include "ringbuffer.h"
+#include "board.h"
 
 /* Endpoint numbers */
 #define DATAOUT     1
@@ -37,7 +38,20 @@
 extern const Pin pinPhoneRST;
 
 enum confNum {
-    CFG_NUM_SNIFF = 1, CFG_NUM_CCID, CFG_NUM_PHONE, CFG_NUM_MITM, NUM_CONF
+	CFG_NUM_NONE	= 0,
+#ifdef HAVE_SNIFFER
+	CFG_NUM_SNIFF,
+#endif
+#ifdef HAVE_CCID
+	CFG_NUM_CCID,
+#endif
+#ifdef HAVE_CARDEM
+	CFG_NUM_PHONE,
+#endif
+#ifdef HAVE_MITM
+	CFG_NUM_MITM,
+#endif
+	NUM_CONF
 };
 
 /// CCIDDriverConfiguration Descriptors