clk: export __clk_round_rate for providers

Commit 99cbd064 ("clk: qcom: Support display RCG clocks") adds
a use of the __clk_round_rate in a clock provided that can be built
as a loadable module.

This exports the symbol to avoid the build error from compiling
the qcom clock as a module.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/clk.c

@@ -1006,6 +1006,7 @@ unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
 	else
 		return clk->rate;
 }
+EXPORT_SYMBOL_GPL(__clk_round_rate);
 
 /**
  * clk_round_rate - round the given rate for a clk