clk: davinci: New driver for davinci PLL clocks

This adds a new driver for mach-davinci PLL clocks. This is porting the
code from arch/arm/mach-davinci/clock.c to the common clock framework.
Additionally, it adds device tree support for these clocks.

The ifeq ($(CONFIG_COMMON_CLK), y) in the Makefile is needed to prevent
compile errors until the clock code in arch/arm/mach-davinci is removed.

Note: although there are similar clocks for TI Keystone we are not able
to share the code for a few reasons. The keystone clocks are device tree
only and use legacy one-node-per-clock bindings. Also the register
layouts are a bit different, which would add even more if/else mess
to the keystone clocks. And the keystone PLL driver doesn't support
setting clock rates.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

include/linux/platform_data/clk-davinci-pll.h

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PLL clock driver for TI Davinci SoCs
+ *
+ * Copyright (C) 2018 David Lechner <david@lechnology.com>
+ */
+
+#ifndef __LINUX_PLATFORM_DATA_CLK_DAVINCI_PLL_H__
+#define __LINUX_PLATFORM_DATA_CLK_DAVINCI_PLL_H__
+
+#include <linux/regmap.h>
+
+/**
+ * davinci_pll_platform_data
+ * @cfgchip: CFGCHIP syscon regmap
+ */
+struct davinci_pll_platform_data {
+	struct regmap *cfgchip;
+};
+
+#endif /* __LINUX_PLATFORM_DATA_CLK_DAVINCI_PLL_H__ */