pinctrl: meson: add GPIO support

This commit adds GPIO support to the Amlogic Meson pin controller
driver, based on code from Linux kernel.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>

arch/arm/include/asm/arch-meson/gpio.h

@@ -0,0 +1,11 @@
+/*
+ * (C) Copyright 2017 - Beniamino Galvani <b.galvani@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __ASM_ARCH_MESON_GPIO_H
+#define __ASM_ARCH_MESON_GPIO_H
+
+
+#endif	/* __ASM_ARCH_MESON_GPIO_H */