PNP: fix name memory leak in pnp_alloc_dev()

After commit 1fa5ae85 ("driver core: get rid of struct device's
bus_id string array"), the name of device is allocated dynamically,
move dev_set_name() after pnp_add_id() to avoid memory leak.

Fixes: 1fa5ae85

 ("driver core: get rid of struct device's bus_id string array")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>