Vulkan: Set EGL_NATIVE_VISUAL_ID for EGL_KHR_platform_gbm Spec requires EGLConfig on GBM platform to report a GBM color format in EGL_NATIVE_VISUAL_ID. Previously this field was left unset. This change ensures compliance by assigning the appropriate GBM color format. Bug: angleproject:7829 Change-Id: I6c5a23374824c444e0de0b6592ea31eb855722e4 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6882716 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>