drivers: tty: serial: Add missing of_node_put() in serial-tegra.c

In tegra_uart_init(), of_find_matching_node() 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>
Link: https://lore.kernel.org/r/20220615111747.3963930-1-windhl@126.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>