[S390] cio: handle failed disable_subchannel after device recognition

Handle a failing cio_disable_subchannel at the end of our device
recognition as if the recognition itself failed. This way
subsequent registration steps do not need to handle enabled
subchannels.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>