iotests: Remove the superfluous 2nd check for the availability of quorum

Commit d9df28e ("iotests: check whitelisted formats") added the
modern @iotests.skip_if_unsupported() to the functions in this test,
so we don't need the old explicit test here anymore.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20200129141751.32652-1-thuth@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Tested-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

tests/qemu-iotests/139

@@ -344,9 +344,6 @@ class TestBlockdevDel(iotests.QMPTestCase):
 
     @iotests.skip_if_unsupported(['quorum'])
     def testQuorum(self):
-        if not iotests.supports_quorum():
-            return
-
         self.addQuorum('quorum0', 'node0', 'node1')
         # We cannot remove the children of a Quorum device
         self.delBlockDriverState('node0', expect_error = True)