clk: clk-mux: Make public the clk_fetch_parent_index

Make public the clk_fetch_parent_index and rename it. This allow
us to be reused in driver specialization

Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index b8acacd..59f9c24 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -74,6 +74,7 @@
 #define to_clk_mux(_clk) container_of(_clk, struct clk_mux, clk)
 extern const struct clk_ops clk_mux_ops;
 u8 clk_mux_get_parent(struct clk *clk);
+int clk_mux_fetch_parent_index(struct clk *clk, struct clk *parent);
 
 /**
  * clk_mux_index_to_val() - Convert the parent index to the register value