Fix default provider merge glitch

Property "default" no longer exists, replace "default=yes" with
"provider=default"
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/11150)

providers/defltprov.c

@@ -384,7 +384,7 @@ static const OSSL_ALGORITHM deflt_signature[] = {
 #ifndef OPENSSL_NO_DSA
     { "DSA:dsaEncryption", "provider=default", dsa_signature_functions },
 #endif
-    { "RSA:rsaEncryption", "default=yes", rsa_signature_functions },
+    { "RSA:rsaEncryption", "provider=default", rsa_signature_functions },
     { NULL, NULL, NULL }
 };