tests: More portable CmdBlitImage format tests

Use mandatory VK_FORMAT_R8G8B8A8_SINT instead of BGRA.
diff --git a/tests/layer_validation_tests.cpp b/tests/layer_validation_tests.cpp
index fbdc747..9cbf1a2 100644
--- a/tests/layer_validation_tests.cpp
+++ b/tests/layer_validation_tests.cpp
@@ -3787,7 +3787,7 @@
     VkImageObj dst_image(m_device);
     dst_image.init(64, 64, VK_FORMAT_B8G8R8A8_UNORM, VK_IMAGE_USAGE_TRANSFER_DST_BIT, VK_IMAGE_TILING_LINEAR, 0);
     VkImageObj dst_image2(m_device);
-    dst_image2.init(64, 64, VK_FORMAT_B8G8R8A8_SINT, VK_IMAGE_USAGE_TRANSFER_DST_BIT, VK_IMAGE_TILING_LINEAR, 0);
+    dst_image2.init(64, 64, VK_FORMAT_R8G8B8A8_SINT, VK_IMAGE_USAGE_TRANSFER_DST_BIT, VK_IMAGE_TILING_LINEAR, 0);
 
     VkImageBlit blitRegion = {};
     blitRegion.srcSubresource.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;