add capability for TelephonyManager.getNetworkSlicingConfiguration()

- add comment to specify HAL interface getSlicingConfig() which is used
  by TelephonyManager.getNetworkSlicingConfiguration() is in the reduced
  feature set.
- allow REQUEST_NOT_SUPPORTED for HAL interface getSlicingConfig() and
  update related VTS test case.

Bug: 181713905
Test: run "atest VtsHalRadioV1_6TargetTest" and check the result for
      getSlicingConfig is PASSED
[3/17] PerInstance/RadioHidlTest_v1_6#getSlicingConfig/0_slot1: PASSED (9ms)

Change-Id: Ia318b8225e8b0e772a85bb9909f2e0114e0ae6e3
diff --git a/radio/1.6/IRadioResponse.hal b/radio/1.6/IRadioResponse.hal
index 883711c..805586b 100644
--- a/radio/1.6/IRadioResponse.hal
+++ b/radio/1.6/IRadioResponse.hal
@@ -433,6 +433,7 @@
      *   RadioError:RADIO_NOT_AVAILABLE
      *   RadioError:INTERNAL_ERR
      *   RadioError:MODEM_ERR
+     *   RadioError:REQUEST_NOT_SUPPORTED
      */
     oneway getSlicingConfigResponse(RadioResponseInfo info,
             SlicingConfig slicingConfig);
diff --git a/radio/1.6/vts/functional/radio_hidl_hal_api.cpp b/radio/1.6/vts/functional/radio_hidl_hal_api.cpp
index 7fde18e..70abc4b 100644
--- a/radio/1.6/vts/functional/radio_hidl_hal_api.cpp
+++ b/radio/1.6/vts/functional/radio_hidl_hal_api.cpp
@@ -172,7 +172,13 @@
     EXPECT_EQ(std::cv_status::no_timeout, wait());
     EXPECT_EQ(RadioResponseType::SOLICITED, radioRsp_v1_6->rspInfo.type);
     EXPECT_EQ(serial, radioRsp_v1_6->rspInfo.serial);
-    EXPECT_EQ(::android::hardware::radio::V1_6::RadioError::NONE, radioRsp_v1_6->rspInfo.error);
+    if (getRadioHalCapabilities().modemReducedFeatureSet1) {
+        ASSERT_TRUE(CheckAnyOfErrors(
+                radioRsp_v1_6->rspInfo.error,
+                {::android::hardware::radio::V1_6::RadioError::REQUEST_NOT_SUPPORTED}));
+    } else {
+        EXPECT_EQ(::android::hardware::radio::V1_6::RadioError::NONE, radioRsp_v1_6->rspInfo.error);
+    }
 }
 
 /*