hw/display/vmware_vga: Remove dependency on VNC header

hw/display/vmware_vga: Remove dependency on VNC header

In commit 2f487a3d40faff1 we fixed a problem observed with using the
vmware-vga device and the VNC UI frontend in a belt-and-braces
manner:
 * we made the VNC frontend handle non-multiple-of-16 surface widths
 * we rounded up the vmware-vga display width to a multiple of 16

However this introduced a spurious dependency of a device model on a
UI frontend header.  vmware-vga isn't special and should not care
about what UI frontend it is using, and the VNC frontend needs to
handle arbitrary surface widths because other display device models
could use them.  Moreover, even if the maximum width in vmware-vga is
made a multiple of 16, the guest itself can always program a
different width.

Remove the dependency on the VNC header.  Since we have been using
the rounded-up width value since 2014, stick with it rather than
introducing a behaviour change, but don't calculate it by rounding up
to VNC_DIRTY_BITS_PER_PIXEL any more.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20210112161608.16055-1-peter.maydell@linaro.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>