clk: add common of_clk_init() function

Modify of_clk_init function so that it will determine which
driver to initialize based on device tree instead of each driver
registering to it.

Based on a similar patch for drivers/irqchip by Thomas Petazzoni and
drivers/clocksource by Stephen Warren.

Signed-off-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Tested-by: Tony Prisk <linux@prisktech.co.nz>
Tested-by: Pawel Moll <pawel.moll@arm.com>
Tested-by: Rob Herring <rob.herring@calxeda.com>
Tested-by: Josh Cartwright <josh.cartwright@ni.com>
Reviewed-by: Josh Cartwright <josh.cartwright@ni.com>
Acked-by: Maxime Ripard <maxime.ripard@anandra.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: merge conflict from missing CLKSRC_OF_TABLES()]

Signed-off-by: Mike Turquette <mturquette@linaro.org>
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 4989b8a..7f197d7 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -379,7 +379,13 @@
 };
 struct clk *of_clk_src_onecell_get(struct of_phandle_args *clkspec, void *data);
 const char *of_clk_get_parent_name(struct device_node *np, int index);
+
 void of_clk_init(const struct of_device_id *matches);
 
+#define CLK_OF_DECLARE(name, compat, fn)			\
+	static const struct of_device_id __clk_of_table_##name	\
+		__used __section(__clk_of_table)		\
+		= { .compatible = compat, .data = fn };
+
 #endif /* CONFIG_COMMON_CLK */
 #endif /* CLK_PROVIDER_H */