This reverts commit 7b401c3b.

Until libvirt is able to differentiate whether heads='1' is just a
leftover from previous libvirt or whether that's added by user on
purpose and also whether the domain was started with the support for
qxl's max_outputs, we cannot incorporate this patch into the tree
due to compatibility reasons.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>