PM / devfreq: Move governor.h to a public header location

Some device drivers (and out-of-tree modules) might want to define
device-specific device governors. Rather than restricting all of them to
be a part of drivers/devfreq/ (which is not possible for out-of-tree
drivers anyway) move governor.h to include/linux/devfreq-governor.h and
update all drivers to use it.

The devfreq_cpu_data is only used internally, by the passive governor,
so it is moved to the driver source rather than being a part of the
public interface.

Reported-by: Robie Basak <robibasa@qti.qualcomm.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://patchwork.kernel.org/project/linux-pm/patch/20251030-governor-public-v2-1-432a11a9975a@oss.qualcomm.com/

drivers/devfreq/governor_powersave.c

@@ -7,8 +7,8 @@
  */
 
 #include <linux/devfreq.h>
+#include <linux/devfreq-governor.h>
 #include <linux/module.h>
-#include "governor.h"
 
 static int devfreq_powersave_func(struct devfreq *df,
 				  unsigned long *freq)