iotests: Update 082 expected output

A recent tweak to the '-o help' output for qemu-img needs to be
reflected into the iotests expected outputs.

Fixes: f7077c98
Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>