ARM: OMAP2+: display: Fix refcount leak bug

In omapdss_init_fbdev(), of_find_node_by_name() will return a node
pointer with refcount incremented. We should use of_node_put() when
it is not used anymore.

Signed-off-by: Liang He <windhl@126.com>
Message-Id: <20220617145803.4050918-1-windhl@126.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>