The documentation and help for qemu-img claims that 'qemu-img create'
will take the '--image-opts' argument.  This is not true, so this
patch removes those claims.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>