suites/4g: Wait for IP addr received before trying to use the link
Otherwise processes using the link like "ping" or "iperf3" may fail
because there's still no IP address assigned.
Change-Id: I28137f10a19db01fe90b24830a60342a448d1e92
diff --git a/sysmocom/suites/4g/rrc_idle_mt_ping.py b/sysmocom/suites/4g/rrc_idle_mt_ping.py
index 7caba32..fb3c32c 100755
--- a/sysmocom/suites/4g/rrc_idle_mt_ping.py
+++ b/sysmocom/suites/4g/rrc_idle_mt_ping.py
@@ -16,7 +16,7 @@
ue.connect(enb)
print('waiting for UE to attach...')
-wait(ue.is_rrc_connected)
+wait(ue.is_registered)
print('UE is RRC connected')
print('waiting until RRC connection gets released...')