vga: Add mechanism to force the use of a shadow surface

This prevents surface sharing which will be necessary to
fix cirrus HW cursor support.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
cirrus: Force use of shadow pixmap when HW cursor is enabled

The HW cursor cannot be painted on a shared surface. This fixes HW
cursor display in Windows NT 4.0 and Windows 98.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
move hw cursor pos from cirrus to vga
vga: set catagory bit for secondary vga device

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20141216-1' into staging

cirrus hwcursor fixes.
set secondary-vga category.

# gpg: Signature made Tue 16 Dec 2014 14:44:09 GMT using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"

* remotes/kraxel/tags/pull-vga-20141216-1:
  vga: set catagory bit for secondary vga device
  move hw cursor pos from cirrus to vga
  cirrus: Force use of shadow pixmap when HW cursor is enabled
  vga: Add mechanism to force the use of a shadow surface

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>