sna/present: Postpone recursed vblank during TearFree by 1ms

Avoid postponing until the next vblank to avoid continually recursing
every TearFree update, and to minimise the presentation delay.

References: https://bugs.freedesktop.org/show_bug.cgi?id=94982
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

src/sna/sna_present.c

@@ -394,8 +394,7 @@ sna_present_vblank_handler(struct drm_event_vblank *event)
 
 	if (info->sna->mode.shadow_wait) {
 		DBG(("%s: recursed from TearFree\n", __FUNCTION__));
-		info->target_msc = msc + 1;
-		if (sna_present_queue(info, msc))
+		if (TimerSet(NULL, 0, 1, sna_fake_vblank_handler, info))
 			return;
 	}