blackfin-cpufreq: Mark cpu_set_cclk() as static

The cpu_set_cclk() function was only used in a single source file so far.
Indicate this setting also by the corresponding linkage specifier.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/blackfin-cpufreq.c

@@ -112,7 +112,7 @@ static unsigned int bfin_getfreq_khz(unsigned int cpu)
 }
 
 #ifdef CONFIG_BF60x
-int cpu_set_cclk(int cpu, unsigned long new)
+static int cpu_set_cclk(int cpu, unsigned long new)
 {
 	struct clk *clk;
 	int ret;