iotests: drop some extra ** in qmp() call

qmp() method supports passing dict (if it doesn't need substituting
'_' to '-' in keys). So, drop some extra '**' operators.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20231006154125.1068348-12-vsementsov@yandex-team.ru
Signed-off-by: John Snow <jsnow@redhat.com>
10 files changed