drm/i915/display: Don't use "proxy" headers

The driver uses math.h and not util_macros.h.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231129140129.699767-1-andriy.shevchenko@linux.intel.com

drivers/gpu/drm/i915/display/intel_snps_phy.c

@@ -3,7 +3,7 @@
  * Copyright © 2019 Intel Corporation
  */
 
-#include <linux/util_macros.h>
+#include <linux/math.h>
 
 #include "i915_reg.h"
 #include "intel_ddi.h"