resources.conf: EC20 doesn't support SupplementaryServices

As the interface never appears, tests using the modem fail because we
wait for all the interfaces to be available based on the features
attribute.

Change-Id: I68fcf2b9083966ad42940e1629abe2a1a6b74095
diff --git a/example/resources.conf b/example/resources.conf
index 497626d..c1ab322 100644
--- a/example/resources.conf
+++ b/example/resources.conf
@@ -89,7 +89,7 @@
   ki: 'BB70807226393CDBAC8DD3439FF54252'
   auth_algo: 'xor'
   ciphers: [a5_0, a5_1]
-  features: ['sms', 'ussd', 'gprs']
+  features: ['sms', 'gprs']
 
 - label: gobi2k
   path: '/gobi_3'