mb/system76/cml-u: Add System76 Galago Pro 4

Change-Id: I3dfa2ab430439d8dc71531b92aa7800db94d603b
Signed-off-by: Jeremy Soller <jeremy@system76.com>
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52034
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/mainboard/system76/cml-u/gpio_early.c

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <mainboard/gpio.h>
+#include <soc/gpio.h>
+
+static const struct pad_config early_gpio_table[] = {
+	PAD_CFG_NF(GPP_C20, NONE, DEEP, NF1), // UART2_RXD
+	PAD_CFG_NF(GPP_C21, NONE, DEEP, NF1), // UART2_TXD
+};
+
+void mainboard_configure_early_gpios(void)
+{
+	gpio_configure_pads(early_gpio_table, ARRAY_SIZE(early_gpio_table));
+}