USB: small fix in error case of suspend in generic usbserial code

usb:usbserial: fix flags in error case of suspension

suspended flag must be reset in error case

Signed-off-by: Oliver Neukum <oliver@neukum.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>