slimbus: qcom-ngd: Add error handling in of_qcom_slim_ngd_register

No error handling is performed when platform_device_add()
return fails. Refer to the error handling of driver_set_override(),
add error handling for platform_device_add().

Fixes: 917809e2 ("slimbus: ngd: Add qcom SLIMBus NGD driver")
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Lin Yujun <linyujun809@huawei.com>
Link: https://lore.kernel.org/r/20220914031953.94061-1-linyujun809@huawei.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>