Vulkan: Remove support for GL_RGB8 from DisplayVkAndroid

The Android Vulkan loader doesn't support GL_RGB8, so remove it from
DisplayVkAndroid::generateConfigs().

The list of supported swapchain formats is available at:
    https://cs.android.com/android/platform/superproject/+/master:frameworks/native/vulkan/libvulkan/swapchain.cpp;l=465-486?q=GetNativePixelFormat

This fixes launching the Zillow app.

Bug: angleproject:6277
Change-Id: I34f06e2b45a1de77864701462bf11712285b7ae2
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3235466
Commit-Queue: Tim Van Patten <timvp@google.com>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Ian Elliott <ianelliott@google.com>

src/libANGLE/renderer/vulkan/android/DisplayVkAndroid.cpp

@@ -50,9 +50,11 @@ SurfaceImpl *DisplayVkAndroid::createWindowSurfaceVk(const egl::SurfaceState &st
 
 egl::ConfigSet DisplayVkAndroid::generateConfigs()
 {
+    // The list of supported swapchain formats is available at:
+    // https://cs.android.com/android/platform/superproject/+/master:frameworks/native/vulkan/libvulkan/swapchain.cpp;l=465-486?q=GetNativePixelFormat
     // TODO (Issue 4062): Add conditional support for GL_RGB10_A2 and GL_RGBA16F when the
     // Android Vulkan loader adds conditional support for them.
-    const std::array<GLenum, 3> kColorFormats = {GL_RGBA8, GL_RGB8, GL_RGB565};
+    const std::array<GLenum, 2> kColorFormats = {GL_RGBA8, GL_RGB565};
 
     std::vector<GLenum> depthStencilFormats(
         egl_vk::kConfigDepthStencilFormats,