qemu-iotests: ignore fragmentation information for qed

We added image fragmentation statistics functions to qemu-img several days
ago, those patches will cause "./check -qed" failed. This patch will ignore
fragmentation statistics information of qed format, and then "./check -qed"
will work.

Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
