coresight: fixing validity check on remote device

A validity check should be made on the remote device, i.e rdev,
rather than the current device.

Signed-off-by: Kaixu Xia <xiakaixu@huawei.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 2ccffaf92e7b7cc9dfa6c3458fc9cb151621680a)
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>