net: appletalk: Fix device refcount leak in atrtr_create()

When updating an existing route entry in atrtr_create(), the old device
reference was not being released before assigning the new device,
leading to a device refcount leak. Fix this by calling dev_put() to
release the old device reference before holding the new one.

Fixes: c7f905f0 ("[ATALK]: Add missing dev_hold() to atrtr_create().")
Signed-off-by: Kito Xu <veritas501@foxmail.com>
Link: https://patch.msgid.link/tencent_E1A26771CDAB389A0396D1681A90A49E5D09@qq.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>