coresight: Remove redundant null pointer check before of_node_put and put_device

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

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>