drm/i915: Set PKG_C_LATENCY.added_wake_time to 0

AFAIK PKG_C_LATENCY.added_wake_time only matters for flip queue.
As long as we're not using that there's no point in adding any
extra wake time.

Reviewed-by: Uma Shankar <[e-mail]>
Signed-off-by: Ville Syrjälä <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

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

···
 #include "skl_watermark.h"
 #include "skl_watermark_regs.h"
 
-/*It is expected that DSB can do posted writes to every register in
- * the pipe and planes within 100us. For flip queue use case, the
- * recommended DSB execution time is 100us + one SAGV block time.
- */
-#define DSB_EXE_TIME 100
-
 struct intel_dbuf_state {
 	struct intel_global_state base;
 
···
 	}
 
 	if (fixed_refresh_rate) {
-		added_wake_time = DSB_EXE_TIME +
-			display->sagv.block_time_us;
-
 		latency = skl_watermark_max_latency(display, 1);
 
 		/* Wa_22020432604 */