esp32/boards/GENERIC_C3: Merge with GENERIC_C3_USB.

As the IDF no longer supports earlier revisions of the C3 by default, we
now just explicitly support rev 3+ and enable USB (which wasn't supported
in earlier revisions).

This work was funded through GitHub Sponsors.
Signed-off-by: NJim Mussared <jim.mussared@gmail.com>

ports/esp32/boards/GENERIC_C3/board.md

+The following files are firmware images that should work on most
+ESP32-C3-based boards with 4MiB of flash, including WROOM and MINI modules,
+that use the revision 3 silicon (or newer).
+
+USB serial/JTAG support is enabled on pin 18 and 19. Note that this
+is not a full USB stack, the C3 just provides a CDC/ACM class serial
+and JTAG interface.

ports/esp32/boards/GENERIC_C3/mpconfigboard.cmake

@@ -3,4 +3,5 @@ set(IDF_TARGET esp32c3)
 set(SDKCONFIG_DEFAULTS
     boards/sdkconfig.base
     boards/sdkconfig.ble
+    boards/GENERIC_C3/sdkconfig.c3usb
 )

ports/esp32/boards/GENERIC_C3_USB/board.json

-{
-    "deploy": [
-        "../deploy_c3.md"
-    ],
-    "docs": "",
-    "features": [
-        "BLE",
-        "External Flash",
-        "WiFi"
-    ],
-    "id": "esp32c3-usb",
-    "images": [
-        "esp32c3_devkitmini.jpg"
-    ],
-    "mcu": "esp32c3",
-    "product": "ESP32-C3 with USB",
-    "thumbnail": "",
-    "url": "https://www.espressif.com/en/products/modules",
-    "vendor": "Espressif"
-}

ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.cmake

-set(IDF_TARGET esp32c3)
-
-set(SDKCONFIG_DEFAULTS
-    boards/sdkconfig.base
-    boards/sdkconfig.ble
-    boards/GENERIC_C3_USB/sdkconfig.board
-)

ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.h

-// This configuration is for a generic ESP32C3 board with 4MiB (or more) of flash.
-
-#define MICROPY_HW_BOARD_NAME               "ESP32C3 module"
-#define MICROPY_HW_MCU_NAME                 "ESP32C3"
-
-#define MICROPY_HW_ENABLE_SDCARD            (0)
-#define MICROPY_PY_MACHINE_DAC              (0)
-#define MICROPY_PY_MACHINE_I2S              (0)