soc: Add initial ESP32-C3 support

From internal commit 7761d6e8

components/soc/esp32c3/sigmadelta_periph.c

@@ -0,0 +1,33 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "soc/sigmadelta_periph.h"
+#include "soc/gpio_sig_map.h"
+
+const sigma_delta_signal_conn_t sigma_delta_periph_signals = {
+    .channels = {
+        [0] = {
+            GPIO_SD0_OUT_IDX
+        },
+        [1] = {
+            GPIO_SD1_OUT_IDX
+        },
+        [2] = {
+            GPIO_SD2_OUT_IDX
+        },
+        [3] = {
+            GPIO_SD3_OUT_IDX
+        }
+    }
+};