Fix range_should_be_prefix() to actually return the correct result

range_should_be_prefix() was misidentifying whether an IP address range
should in fact be represented as a prefix. This was due to a bug introduced
in commit 42d7d7dd which made this incorrect change:

-    OPENSSL_assert(memcmp(min, max, length) <= 0);
+    if (memcmp(min, max, length) <= 0)
+        return -1;

This error leads to incorrect DER being encoded/accepted.

Reported by Theo Buehler (@botovq)

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18524)
