acts - avoid running S API tests on R

This MAC randomization test uses an API that is only avaiable on S.
Avoid running this test if the device is not at least S.

Bug: 183504451
Test: compile
Change-Id: I3db8a9bae77a85c06ff3edbdbb9b7ec90054e619
diff --git a/acts_tests/tests/google/wifi/WifiMacRandomizationTest.py b/acts_tests/tests/google/wifi/WifiMacRandomizationTest.py
index d779529..fdfd8a0 100644
--- a/acts_tests/tests/google/wifi/WifiMacRandomizationTest.py
+++ b/acts_tests/tests/google/wifi/WifiMacRandomizationTest.py
@@ -634,6 +634,9 @@
             4. Connect to the network. Verify the MAC address is random and
                different from the randomized MAC observed in step 2.
         """
+        asserts.skip_if(not self.dut.droid.isSdkAtLeastS(),
+                        "This feature is only supported on S and later.")
+
         network_suggestion = self.reference_networks[0]["5g"]
         network_suggestion["enhancedMacRandomizationEnabled"] = True