Rename module ofono_client as modem

Change-Id: I43b51ae937d87d6d4e18caea59f9366e2e28c9f2
diff --git a/src/osmo_gsm_tester/resource.py b/src/osmo_gsm_tester/resource.py
index 1bacd38..746aae0 100644
--- a/src/osmo_gsm_tester/resource.py
+++ b/src/osmo_gsm_tester/resource.py
@@ -27,7 +27,7 @@
 from . import config
 from . import util
 from . import schema
-from . import ofono_client
+from . import modem
 from . import osmo_nitb
 from . import bts_sysmo, bts_osmotrx, bts_octphy