We select the feedback tranche according to the image format but not the
actual format that we will use for presentation. This breaks direct
scanout in cases where the application selected a visual with an alpha
channel but using EGL_EXT_present_opaque which previously worked as
expected.
Fix this by selecting the feedback tranche according to the actual
presentation format.
Fixes: 9ea9a963aa ("egl/wayland: Fix EGL_EXT_present_opaque")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28153>