cpufreq: intel_pstate: Do not include debugfs.h

The intel_pstate driver doesn't use debugfs any more, so drop
linux/debugfs.h from the list of included headers in it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/intel_pstate.c

@@ -26,7 +26,6 @@
 #include <linux/sysfs.h>
 #include <linux/types.h>
 #include <linux/fs.h>
-#include <linux/debugfs.h>
 #include <linux/acpi.h>
 #include <linux/vmalloc.h>
 #include <trace/events/power.h>