[S390] cio: move options to io_sch_private

Move the options member from struct subchannel to
io_subchannel_private since it's I/O subchannel specific.
Also remove the unused cio_get_options function.

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