gpio: sandbox: cleanup binding support

Cleanup binding support, use the generic binding by default
(test u-class gpio_xlate_offs_flags function) and add
specific binding for added value.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/dt-bindings/gpio/sandbox-gpio.h

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This header provides constants for binding sandbox,gpio
+ *
+ */
+#ifndef _DT_BINDINGS_GPIO_SANDBOX_GPIO_H
+#define _DT_BINDINGS_GPIO_SANDBOX_GPIO_H
+
+/*
+ * Add a specific binding for sandbox gpio.
+ * The value need to be after the generic defines of
+ * dt-bindings/gpio/gpio.h
+ */
+
+/* Bit 16 express GPIO input mode */
+#define GPIO_IN			0x10000
+
+/* Bit 17 express GPIO output mode */
+#define GPIO_OUT		0x20000
+
+/* Bit 18 express GPIO output is active */
+#define GPIO_OUT_ACTIVE		0x40000
+
+#endif