fardump: remove a warning that is caused by gcc, not by the source code

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
diff --git a/fardump.c b/fardump.c
index ef63679..5a22c81 100644
--- a/fardump.c
+++ b/fardump.c
@@ -232,7 +232,7 @@
 	case TYPE_HEX:
 	case TYPE_OCTAL:;
 		uint64_t v;
-		char *format;
+		char *format = NULL;
 
 		if (len != 8) {
 			printf("invalid length for integer type attribute\n");