tests: Use 4x MSAA rather than 2x.

These tests don't bother to check if it's available, so use something
that's guaranteed.

Avoids bad behavior on Anvil for Haswell.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
diff --git a/tests/layer_validation_tests.cpp b/tests/layer_validation_tests.cpp
index ec15459..a16f25b 100644
--- a/tests/layer_validation_tests.cpp
+++ b/tests/layer_validation_tests.cpp
@@ -8650,7 +8650,7 @@
 
     ASSERT_NO_FATAL_FAILURE(InitState());
 
-    // Create two images of sample count 2 and try to Resolve between them
+    // Create two images of sample count 4 and try to Resolve between them
     VkImage srcImage;
     VkImage dstImage;
     VkDeviceMemory srcMem;
@@ -8667,7 +8667,7 @@
     image_create_info.extent.depth = 1;
     image_create_info.mipLevels = 1;
     image_create_info.arrayLayers = 1;
-    image_create_info.samples = VK_SAMPLE_COUNT_2_BIT;
+    image_create_info.samples = VK_SAMPLE_COUNT_4_BIT;
     image_create_info.tiling = VK_IMAGE_TILING_OPTIMAL;
     // Note: Some implementations expect color attachment usage for any
     // multisample surface