qemu-iotests: Use qemu-io -f $IMGFMT

qemu-iotests: Use qemu-io -f $IMGFMT

This patch changes $QEMU_IO so that all tests by default pass a format
argument to qemu-io.

There are a few cases where -f $IMGFMT is not wanted because it selects
the wrong driver or json: filenames including a driver are used. They
are changed to use $QEMU_IO_PROG, which doesn't include any options.

Tests 071 and 081 have output changes because now the actual request
fails instead of reading the 2k probing buffer.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1416497234-29880-3-git-send-email-kwolf@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>