drm/i915: reduce includes in intel_fifo_underrun.h

Only include what's needed.
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/29b57e168e8af842baad2626959cea258402a2c1.1667383630.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_fifo_underrun.h

@@ -8,9 +8,8 @@
 
 #include <linux/types.h>
 
-#include "intel_display.h"
-
 struct drm_i915_private;
+enum pipe;
 
 bool intel_set_cpu_fifo_underrun_reporting(struct drm_i915_private *dev_priv,
 					   enum pipe pipe, bool enable);