macintosh/windfarm_smu_sat: Add missing of_node_put()

We call of_node_get() in wf_sat_probe() after sat is created,
so we need the of_node_put() before *kfree(sat)*.

Fixes: ac171c46 ("[PATCH] powerpc: Thermal control for dual core G5s")
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230330033558.2562778-1-windhl@126.com