cert_create: merge successive i2d_ASN1_INTEGER() calls

The ext_new_nvcounter() function calls i2d_ASN1_INTEGER() twice;
the first call to get the return value "sz", and the second one
for writing data into the buffer.  This is actually redundant.
We can do both by one function call.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

tools/cert_create/src/ext.c

@@ -262,8 +262,7 @@ X509_EXTENSION *ext_new_nvcounter(int nid, int crit, int value)
 	/* Encode counter */
 	counter = ASN1_INTEGER_new();
 	ASN1_INTEGER_set(counter, value);
-	sz = i2d_ASN1_INTEGER(counter, NULL);
-	i2d_ASN1_INTEGER(counter, &p);
+	sz = i2d_ASN1_INTEGER(counter, &p);
 
 	/* Create the extension */
 	ex = ext_new(nid, crit, p, sz);