hw/pci-host/designware: Fix viewport configuration

hw/pci-host/designware: Fix viewport configuration

Commit 6970f91ac781, "hw/pci-host/designware: Use deposit/extract
API" accidentally introduced a copy-and-paste error, causing Linux
6.14 to hang when initializing the PCIe bridge on the imx8mp-evk
machine.  This fix corrects the error.

Fixes: 6970f91ac781 ("hw/pci-host/designware: Use deposit/extract API")
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250501183445.2389-3-shentey@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>