drm/i915: fix applying placement flag

Switching from a separate list to flags introduced a bug here.

We were accidentially ORing the flag before initailizing the placement
and not after. So this code didn't do nothing except producing a
warning.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: a78a8da ("drm/ttm: replace busy placement with flags v6")
Link: https://patchwork.freedesktop.org/patch/msgid/20240226142759.93130-1-christian.koenig@amd.com
Tested-by: Stephen Rothwell <sfr@canb.auug.org.au>	# compile only
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>

Author: Christian König

drivers/gpu/drm/i915/gem/i915_gem_ttm.c

@@ -162,10 +162,10 @@ i915_ttm_placement_from_obj(const struct drm_i915_gem_object *obj,
 	unsigned int flags = obj->flags;
 	unsigned int i;
 
-	places[0].flags |= TTM_PL_FLAG_DESIRED;
 	i915_ttm_place_from_region(num_allowed ? obj->mm.placements[0] :
 				   obj->mm.region, &places[0], obj->bo_offset,
 				   obj->base.size, flags);
+	places[0].flags |= TTM_PL_FLAG_DESIRED;
 
 	/* Cache this on object? */
 	for (i = 0; i < num_allowed; ++i) {