drm/i915/icl: Don't update enabled dbuf slices struct until updated in hw

Do not update number of enabled dbuf slices in dev_priv struct until we
actually enable/disable dbuf slice in hw. This is leading to never
updating dbuf slices and resulting in DBuf slice mismatch warning.

Fixes: aa9664ffe863 ("drm/i915/icl: Enable 2nd DBuf slice only when needed")
Reviewed-by: Paulo Zanoni <[e-mail]>
Signed-off-by: Mahesh Kumar <[e-mail]>
Signed-off-by: Paulo Zanoni <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/i915/intel_pm.c

···
 	       sizeof(dst->ddb.uv_plane[pipe]));
 	memcpy(dst->ddb.plane[pipe], src->ddb.plane[pipe],
 	       sizeof(dst->ddb.plane[pipe]));
-	dst->ddb.enabled_slices = src->ddb.enabled_slices;
 }
 
 static void