Revert "resources.conf: EC20 doesn't support SupplementaryServices"

This reverts commit 31b7f0f9dea3f6f00230022a12612b6750018be6.

EC20 actually supports the feature. I was wrong mainly due to 2 reasons:
- I somehow failed to set the modem Online before checking for the
interface, and in that case it is not shown.
- The test I saw failing in prod is due to /gobi_0 being actually a
gobi2000 there, and the once failing was actually the gobi2000 and not
the EC20.

Change-Id: I31ad35b718e20168a75930498901015ca2015a52
diff --git a/example/resources.conf b/example/resources.conf
index 1672d91..35e3a2d 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', 'gprs']
+  features: ['sms', 'ussd', 'gprs']
 
 - label: gobi2k
   path: '/gobi_3'