Revert "cirrus: allow zero source pitch in pattern fill rops"

This reverts commit 5858dd18.

Conflicts:
	hw/display/cirrus_vga.c

Cc: Wolfgang Bumiller <w.bumiller@proxmox.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Message-id: 1486645341-5010-2-git-send-email-kraxel@redhat.com