layers: A few minor clean-ups from code review

Better use of auto and killing some unneeded code.
diff --git a/tests/layer_validation_tests.cpp b/tests/layer_validation_tests.cpp
index 2ffaa4e..0ea2e69 100644
--- a/tests/layer_validation_tests.cpp
+++ b/tests/layer_validation_tests.cpp
@@ -6874,9 +6874,6 @@
     VkFormatProperties format_properties;
     VkResult err = VK_SUCCESS;
     vkGetPhysicalDeviceFormatProperties(gpu(), VK_FORMAT_B8G8R8A8_UNORM, &format_properties);
-    if (!(format_properties.optimalTilingFeatures & VK_FORMAT_FEATURE_SAMPLED_IMAGE_BIT)) {
-        return;
-    }
 
     ASSERT_NO_FATAL_FAILURE(InitState());
     ASSERT_NO_FATAL_FAILURE(InitRenderTarget());
@@ -6893,7 +6890,7 @@
     image_ci.arrayLayers = 1;
     image_ci.samples = VK_SAMPLE_COUNT_1_BIT;
     image_ci.tiling = VK_IMAGE_TILING_OPTIMAL;
-    image_ci.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;
+    image_ci.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
     image_ci.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
     image_ci.flags = 0;
     VkImage image;