egl/wayland: use __DRI_IMAGE_USE_SCANOUT for the colorbuffer
Matches what is done in dri3_alloc_render_buffer: __DRI_IMAGE_USE_SCANOUT is used when allocating the renderbuffer and different_gpu is false and no modifiers is used.
Matches what is done in dri3_alloc_render_buffer: __DRI_IMAGE_USE_SCANOUT is used when allocating the renderbuffer and different_gpu is false and no modifiers is used.