Allow modification of ro.telephony.default_network

Unfortunately the type of ro.telephony.default_network was changed in
b/110626665 after finalizing Android P.

So modification of ro.telephony.default_network should be allowed.

Bug: 110626665
Test: run vts -m VtsTrebleSysProp
Merged-In: I82bc5d931197684be9f5ca623a55f42cbdc1fd84
Change-Id: Ib22bbc027da956ffb3a01a7a967cb4b8f3d9cb3e
diff --git a/system_property/VtsTrebleSysPropTest.py b/system_property/VtsTrebleSysPropTest.py
index 00fc556..53a3d01 100644
--- a/system_property/VtsTrebleSysPropTest.py
+++ b/system_property/VtsTrebleSysPropTest.py
@@ -41,6 +41,8 @@
                                              contexts file.
         _VENDOR_OR_ODM_NAMEPACES: The namepsaces allowed for vendor/odm
                                   properties.
+        _MODIFIABLE_PROPERTIES: System properties modified officially after
+                                Android P release.
     """
 
     _PUBLIC_PROPERTY_CONTEXTS_FILE_PATH = ("vts/testcases/security/"
@@ -66,6 +68,9 @@
             "persist.vendor.",
             "vendor."
     ]
+    _MODIFIABLE_PROPERTIES = [
+            "ro.telephony.default_network"
+    ]
 
     def setUpClass(self):
         """Initializes tests.
@@ -154,6 +159,8 @@
             public_tokens = pub_property_dict[name]
             asserts.assertTrue(name in sys_property_dict,
                                "Exported property (%s) doesn't exist" % name)
+            if name in self._MODIFIABLE_PROPERTIES:
+                continue
             system_tokens = sys_property_dict[name]
             asserts.assertEqual(public_tokens, system_tokens,
                                 "Exported property (%s) is modified" % name)