drm/i915: move drps, rps and rc6-related functions to intel_pm

This moves DRPS, RPS and RC6-related functionality into intel_pm module.

It also removes the linux/cpufreq.h include from intel_display, as its
only user was the GPU turbo-related functionality in Gen6+ code path.

v2: rebase on top of latest drm-intel-next-queued adding the bits that
shifted around since the last patch.
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_drv.h

@@ -396,6 +396,7 @@ extern void intel_crtc_fb_gamma_set(struct drm_crtc *crtc, u16 red, u16 green,
 extern void intel_crtc_fb_gamma_get(struct drm_crtc *crtc, u16 *red, u16 *green,
 				    u16 *blue, int regno);
 extern void intel_enable_clock_gating(struct drm_device *dev);
+extern void ironlake_disable_rc6(struct drm_device *dev);
 extern void ironlake_enable_drps(struct drm_device *dev);
 extern void ironlake_disable_drps(struct drm_device *dev);
 extern void gen6_enable_rps(struct drm_i915_private *dev_priv);