drm/i915/pm: hide struct drm_i915_clock_gating_funcs

The struct is only needed in intel_pm.c, move it there.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/63779ac0472895803113180818ecadc22c10369e.1643896905.git.jani.nikula@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -107,6 +107,7 @@
 #include "i915_vma.h"
 
 struct dpll;
+struct drm_i915_clock_gating_funcs;
 struct drm_i915_gem_object;
 struct drm_i915_private;
 struct intel_atomic_state;
@@ -302,11 +303,6 @@ struct sdvo_device_mapping {
 	u8 ddc_pin;
 };
 
-/* functions used internal in intel_pm.c */
-struct drm_i915_clock_gating_funcs {
-	void (*init_clock_gating)(struct drm_i915_private *dev_priv);
-};
-
 /* functions used for watermark calcs for display. */
 struct drm_i915_wm_disp_funcs {
 	/* update_wm is for legacy wm management */

drivers/gpu/drm/i915/intel_pm.c

@@ -55,6 +55,10 @@
 #include "vlv_sideband.h"
 #include "../../../platform/x86/intel_ips.h"
 
+struct drm_i915_clock_gating_funcs {
+	void (*init_clock_gating)(struct drm_i915_private *i915);
+};
+
 /* Stores plane specific WM parameters */
 struct skl_wm_params {
 	bool x_tiled, y_tiled;