usb: usb_wwan: resume/suspend can be called after port is gone

We cannot unconditionally access any usb-serial port specific
data from the interface driver.  Both supending and resuming
may happen after the port has been removed and portdata is
freed.

Treat ports with no portdata as closed ports to avoid a NULL
pointer dereference on resume.  No need to kill URBs for
removed ports on suspend, avoiding the same NULL pointer
reference there.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>