esp32c3: add smoke tests for a few boards

These boards probably haven't been working since the addition of I2C,
because they were missing some constants in the machine package.

src/machine/board_esp32-c3-devkit-rust-1.go

@@ -64,8 +64,8 @@ const (
 
 // I2C pins
 const (
-	I2C_SCL_PIN = D8
-	I2C_SDA_PIN = D10
+	SCL_PIN = D8
+	SDA_PIN = D10
 )
 
 // USBCDC pins

src/machine/board_esp32c3-12f.go

@@ -46,3 +46,9 @@ const (
 	UART_TX_PIN = TXD
 	UART_RX_PIN = RXD
 )
+
+// I2C pins
+const (
+	SCL_PIN = NoPin
+	SDA_PIN = NoPin
+)

src/machine/board_makerfabs-esp32c3spi35.go

@@ -64,8 +64,8 @@ const (
 // Touchscreen pins
 const (
 	TS_CS_PIN  = D0
-	TS_SDA_PIN = I2C_SDA_PIN
-	TS_SCL_PIN = I2C_SCL_PIN
+	TS_SDA_PIN = SDA_PIN
+	TS_SCL_PIN = SCL_PIN
 )
 
 // MicroSD pins
@@ -90,8 +90,8 @@ const (
 
 // I2C pins
 const (
-	I2C_SDA_PIN = D2
-	I2C_SCL_PIN = D3
+	SDA_PIN = D2
+	SCL_PIN = D3
 )
 
 // SPI pins