resource: Introduce a type attribute to the resource definition

Change-Id: Ie1fd10ec878311b7347118badb1b9dce5b49e976
diff --git a/src/osmo_gsm_tester/resource.py b/src/osmo_gsm_tester/resource.py
index 98651ce..a536e18 100644
--- a/src/osmo_gsm_tester/resource.py
+++ b/src/osmo_gsm_tester/resource.py
@@ -75,6 +75,7 @@
         'bts[].osmo_trx.multi_arfcn': schema.BOOL_STR,
         'arfcn[].arfcn': schema.INT,
         'arfcn[].band': schema.BAND,
+        'modem[].type': schema.STR,
         'modem[].label': schema.STR,
         'modem[].path': schema.STR,
         'modem[].imsi': schema.IMSI,