cpufreq: sa11x0: Fix build breakage after "Expose frequency table"

Fix build breakage introduced by commit 22c8b4f1 (cpufreq: sa11x0:
Expose frequency table).

[rjw: Changelog]
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/arm/mach-sa1100/generic.h

@@ -3,6 +3,7 @@
  *
  * Author: Nicolas Pitre
  */
+#include <linux/cpufreq.h>
 #include <linux/reboot.h>
 
 extern void sa1100_timer_init(void);
@@ -19,8 +20,6 @@ extern void sa11x0_init_late(void);
 extern void sa1110_mb_enable(void);
 extern void sa1110_mb_disable(void);
 
-struct cpufreq_policy;
-
 extern struct cpufreq_frequency_table sa11x0_freq_table[];
 extern unsigned int sa11x0_freq_to_ppcr(unsigned int khz);
 extern unsigned int sa11x0_getspeed(unsigned int cpu);