USB-Serial: Fix error handling of usb_wwan

commit 6c1ee66a0b2bdbd64c078fba684d640cf2fd38a9 upstream.

This fixes an issue where the bulk-in urb used for incoming data transfer
is not resubmitted if the packet recieved contains an error status.  This
results in the driver locking until the port is closed and re-opened.

Tested on a custom board with a Cinterion GSM module.

Signed-off-by: Matt Burtch <matt@grid-net.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>