drm/xe: Assert size of the struct xe_reg

We want to keep the struct xe_reg as small as possible.
Make sure we don't accidentally change its size.
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240314173130.1177-2-michal.wajdeczko@intel.comSigned-off-by: Michał Winiarski <michal.winiarski@intel.com>

drivers/gpu/drm/xe/regs/xe_reg_defs.h

@@ -6,6 +6,8 @@
 #ifndef _XE_REG_DEFS_H_
 #define _XE_REG_DEFS_H_
 
+#include <linux/build_bug.h>
+
 #include "compat-i915-headers/i915_reg_defs.h"
 
 /**
@@ -44,6 +46,7 @@ struct xe_reg {
 		u32 raw;
 	};
 };
+static_assert(sizeof(struct xe_reg) == sizeof(u32));
 
 /**
  * struct xe_reg_mcr - MCR register definition