arm64: zynqmp: Add pinctrl description

ZynqMP pinctrl Linux driver has been merged to 5.13-rc1 kernel. Based on it
DT files can be extended by pinctrl configurations.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

include/dt-bindings/pinctrl/pinctrl-zynqmp.h

@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * MIO pin configuration defines for Xilinx ZynqMP
+ *
+ * Copyright (C) 2020 Xilinx, Inc.
+ */
+
+#ifndef _DT_BINDINGS_PINCTRL_ZYNQMP_H
+#define _DT_BINDINGS_PINCTRL_ZYNQMP_H
+
+/* Bit value for different voltage levels */
+#define IO_STANDARD_LVCMOS33	0
+#define IO_STANDARD_LVCMOS18	1
+
+/* Bit values for Slew Rates */
+#define SLEW_RATE_FAST		0
+#define SLEW_RATE_SLOW		1
+
+#endif /* _DT_BINDINGS_PINCTRL_ZYNQMP_H */