qxl: avoid an oops in the deferred io code.

commit cc87509d87696d7cd393882f5dedea01e03e41a9 upstream.

If we are using deferred io due to plymouth or X.org fbdev driver
we will oops in memcpy due to this pointless multiply here,

removing it fixes fbdev to start and not oops.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>