drivers/net: accept removing device without any port

drivers/net: accept removing device without any port

The ports can be closed (i.e. completely released)
before removing the whole device.
Such case was wrongly considered an error by some drivers.

If the device supports only one port, there is nothing much
to free after the port is closed.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
Reviewed-by: Rosen Xu <rosen.xu@intel.com>
Reviewed-by: Sachin Saxena <sachin.saxena@oss.nxp.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>