Input: sparcspkr - fix refcount leak in bbc_beep_probe

Input: sparcspkr - fix refcount leak in bbc_beep_probe

of_find_node_by_path() calls of_find_node_opts_by_path(),
which returns a node pointer with refcount
incremented, we should use of_node_put() on it when done.
Add missing of_node_put() to avoid refcount leak.

Fixes: 9c1a5077fdca ("input: Rewrite sparcspkr device probing.")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20220516081018.42728-1-linmq006@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>