vulkan/wsi/x11: report device-group present rectangles with prime.

vulkan/wsi/x11: report device-group present rectangles with prime.

dEQP-VK.wsi.xlib.surface.query_devgroup_present_modes with prime
fail when 0 rectangles are reported. While I believe that test
tests this unintentionally (trying to test the VK_INCOMPLETE return),
I believe it makes sense to always return a rectangle.

In particular we require the data from the given rectangle for
presentation even if we use prime and given that prime is completely
transparent for the app it still counts as local from the perspective
as the application.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6071>