rpmsg: Fix possible refcount leak in rpmsg_register_device_override()

rpmsg: Fix possible refcount leak in rpmsg_register_device_override()

rpmsg_register_device_override need to call put_device to free vch when
driver_set_override fails.

Fix this by adding a put_device() to the error path.

Fixes: 8ab10525cfaa ("rpmsg: Fix calling device_lock() on non-initialized device")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Link: https://lore.kernel.org/r/20220624024120.11576-1-hbh25y@gmail.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>