qemu-iotests: Remove _supported_fmt dmg

qemu-iotests doesn't support dmg, and the dmg block driver doesn't
support image creation. Two test cases declare dmg as supported, but
that's obviously wrong for both reasons. Remove the declaration.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

tests/qemu-iotests/183

@@ -43,7 +43,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 . ./common.filter
 . ./common.qemu
 
-_supported_fmt qcow2 raw qed dmg quorum
+_supported_fmt qcow2 raw qed quorum
 _supported_proto file
 _supported_os Linux
 

tests/qemu-iotests/194

@@ -21,7 +21,7 @@
 
 import iotests
 
-iotests.verify_image_format(supported_fmts=['qcow2', 'qed', 'raw', 'dmg'])
+iotests.verify_image_format(supported_fmts=['qcow2', 'qed', 'raw'])
 iotests.verify_platform(['linux'])
 
 with iotests.FilePath('source.img') as source_img_path, \