usb: aspeed-vhub: Fix refcount leak bug in ast_vhub_init_desc()

usb: aspeed-vhub: Fix refcount leak bug in ast_vhub_init_desc()

[ Upstream commit 220fafb4ed04187e9c17be4152da5a7f2ffbdd8c ]

We should call of_node_put() for the reference returned by
of_get_child_by_name() which has increased the refcount.

Fixes: 30d2617fd7ed ("usb: gadget: aspeed: allow to set usb strings in device tree")
Signed-off-by: Liang He <windhl@126.com>
Link: https://lore.kernel.org/r/20220713120528.368168-1-windhl@126.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>