net: usb: remove redundant null pointer check before of_node_put

of_node_put has taken the null pointer check into account. So it is
safe to remove the duplicated check before of_node_put.

Change-Id: I45e15c7a926e85e969f6da6d7581852ec6989df6
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Git-commit: 764ea3714a85bfc0e3e470cee2166b6ef911b9b9
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git


Signed-off-by: Liangliang Lu <luliang@codeaurora.org>