Fix attribute plurals for isolated_compute_allowed

Following the naming convention.

Bug: N/A
Test: m
Change-Id: Ie26d67423f9ee484ea91038143ba763ed8f97e2f
diff --git a/tests/treble_sepolicy_tests.py b/tests/treble_sepolicy_tests.py
index 8abad94..0628d35 100644
--- a/tests/treble_sepolicy_tests.py
+++ b/tests/treble_sepolicy_tests.py
@@ -357,8 +357,8 @@
 
   def checkIsolatedComputeAllowed(tctx, tclass):
     # check if the permission is in isolated_compute_allowed
-    allowedMemberTypes = test_policy.pol.QueryTypeAttribute(Type="isolated_compute_allowed_services", IsAttr=True) \
-      .union(test_policy.pol.QueryTypeAttribute(Type="isolated_compute_allowed_devices", IsAttr=True))
+    allowedMemberTypes = test_policy.pol.QueryTypeAttribute(Type="isolated_compute_allowed_service", IsAttr=True) \
+      .union(test_policy.pol.QueryTypeAttribute(Type="isolated_compute_allowed_device", IsAttr=True))
     return tctx in allowedMemberTypes and tclass in permissionAllowList["isolated_compute_allowed"]