drm/i915: remove intel_guc::ads_engine_usage_size

intel_guc::ads_engine_usage_size was never used since its addition in
commit 77cdd054dd2c (drm/i915/pmu: Connect engine busyness stats from
GuC to pmu). Drop it.

Found by https://github.com/jirislaby/clang-struct.

Signed-off-by: Jiri Slaby (SUSE) <[e-mail]>
Cc: Jani Nikula <[e-mail]>
Cc: Joonas Lahtinen <[e-mail]>
Cc: Rodrigo Vivi <[e-mail]>
Cc: Tvrtko Ursulin <[e-mail]>
Cc: [e-mail]
Acked-by: Jani Nikula <[e-mail]>
Signed-off-by: Rodrigo Vivi <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/i915/gt/uc/intel_guc.h

···
 	u32 ads_golden_ctxt_size;
 	/** @ads_capture_size: size of register lists in the ADS used for error capture */
 	u32 ads_capture_size;
-	/** @ads_engine_usage_size: size of engine usage in the ADS */
-	u32 ads_engine_usage_size;
 
 	/** @lrc_desc_pool_v69: object allocated to hold the GuC LRC descriptor pool */
 	struct i915_vma *lrc_desc_pool_v69;