drm/i915: reduce includes in intel_clock_gating.c

With the refactoring in the file, some excessive includes were left
behind and are now unnecessary. Remove.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240530100747.328631-2-jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_clock_gating.c

@@ -26,11 +26,7 @@
  */
 
 #include "display/i9xx_plane_regs.h"
-#include "display/intel_de.h"
 #include "display/intel_display.h"
-#include "display/intel_display_trace.h"
-#include "display/intel_fbc_regs.h"
-#include "display/skl_watermark.h"
 
 #include "gt/intel_engine_regs.h"
 #include "gt/intel_gt.h"