drm/ttm: Fix ttm_pool_beneficial_order() return type

drm/ttm: Fix ttm_pool_beneficial_order() return type

Fix a nasty copy and paste bug, where the incorrect boolean return type of
the ttm_pool_beneficial_order() helper had a consequence of avoiding
direct reclaim too eagerly for drivers which use this feature (currently
amdgpu).

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Fixes: 7e9c548d3709 ("drm/ttm: Allow drivers to specify maximum beneficial TTM pool size")
Cc: Christian König <christian.koenig@amd.com>
Cc: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v6.19+
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20260227124901.3177-1-tvrtko.ursulin@igalia.com