netdevice: add the case if dev is NULL

netdevice: add the case if dev is NULL

BugLink: https://bugs.launchpad.net/bugs/1971497
commit b37a466837393af72fe8bcb8f1436410f3f173f3 upstream.

Add the case if dev is NULL in dev_{put, hold}, so the caller doesn't
need to care whether dev is NULL or not.

Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Pavel Machek <pavel@denx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>