of: device: Fix missing of_node_put() in of_dma_set_restricted_buffer

We should use of_node_put() for the reference 'node' returned by
of_parse_phandle() which will increase the refcount.

Fixes: fec9b625 ("of: Add plumbing for restricted DMA pool")
Co-authored-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220702014449.263772-1-windhl@126.com