Add mssa configs for vulkan, and simple bug fix

src/gpu/vk/GrVkUtil.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrVkUtil.h"
 
 bool GrPixelConfigToVkFormat(GrPixelConfig config, VkFormat* format) {
@@ skipping 213 matching lines @@
 bool GrSampleCountToVkSampleCount(uint32_t samples, VkSampleCountFlagBits* vkSamples) {
     switch (samples) {
         case 0: // fall through
         case 1:
             *vkSamples = VK_SAMPLE_COUNT_1_BIT;
             return true;
         case 2:
             *vkSamples = VK_SAMPLE_COUNT_2_BIT;
             return true;
         case 4:
-            *vkSamples = VK_SAMPLE_COUNT_2_BIT;
+            *vkSamples = VK_SAMPLE_COUNT_4_BIT;
             return true;
         case 8:
-            *vkSamples = VK_SAMPLE_COUNT_2_BIT;
+            *vkSamples = VK_SAMPLE_COUNT_8_BIT;
             return true;
         case 16:
-            *vkSamples = VK_SAMPLE_COUNT_2_BIT;
+            *vkSamples = VK_SAMPLE_COUNT_16_BIT;
             return true;
         case 32:
-            *vkSamples = VK_SAMPLE_COUNT_2_BIT;
+            *vkSamples = VK_SAMPLE_COUNT_32_BIT;
             return true;
         case 64:
-            *vkSamples = VK_SAMPLE_COUNT_2_BIT;
+            *vkSamples = VK_SAMPLE_COUNT_64_BIT;
             return true;
         default:
             return false;
     }
 }