egl: Also query modifiers when exporting DMABuf

This fixes eglExportDMABUFImageQueryMESA() so it will report the
modififers of the underlying image. Without this information,
re-importing will likely be broken as it is rare these days that no
modifiers are used.

Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Fixes: 8f7338f2 ("egl: add initial EGL_MESA_image_dma_buf_export v2.4")
(cherry picked from commit 08f1cefe)