The BDRV_O_CREAT option is unused inside qemu and partially duplicates
the bdrv_create method.  Remove it, and the -C option to qemu-io which
isn't used in qemu-iotests anyway.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>