HS 2.0 SPP server: Fix aaa_trust_root_cert_url example to use DER

The trust roots in the PPS MO point to a DER encoded X.509 certificate.

Signed-off-by: Jouni Malinen <j@w1.fi>

hs20/server/sql-example.txt

@@ -3,7 +3,7 @@ INSERT INTO osu_config(realm,field,value) VALUES('example.com','friendly_name','
 INSERT INTO osu_config(realm,field,value) VALUES('example.com','spp_http_auth_url','https://subscription-server.osu.example.com/hs20/spp.php?realm=example.com');
 INSERT INTO osu_config(realm,field,value) VALUES('example.com','trust_root_cert_url','https://osu-server.osu.example.com/hs20/files/spp-root-ca.der');
 INSERT INTO osu_config(realm,field,value) VALUES('example.com','trust_root_cert_fingerprint','5b393a9246865569485c2605c3304e48212b449367858299beba9384c4cf4647');
-INSERT INTO osu_config(realm,field,value) VALUES('example.com','aaa_trust_root_cert_url','https://osu-server.osu.example.com/hs20/files/aaa-root-ca.pem');
+INSERT INTO osu_config(realm,field,value) VALUES('example.com','aaa_trust_root_cert_url','https://osu-server.osu.example.com/hs20/files/aaa-root-ca.der');
 INSERT INTO osu_config(realm,field,value) VALUES('example.com','aaa_trust_root_cert_fingerprint','5b393a9246865569485c2605c3304e48212b449367858299beba9384c4cf4647');
 INSERT INTO osu_config(realm,field,value) VALUES('example.com','free_account','free');
 INSERT INTO osu_config(realm,field,value) VALUES('example.com','policy_url','https://subscription-server.osu.example.com/hs20/spp.php?realm=example.com');