Vulkan fixes for TesselatingPathRenderer test

src/gpu/vk/GrVkUniformBuffer.h

Index: src/gpu/vk/GrVkUniformBuffer.h
diff --git a/src/gpu/vk/GrVkUniformBuffer.h b/src/gpu/vk/GrVkUniformBuffer.h
index bfaf240a65f69a90a327903834c4d473d8262762..ed6c8a0aaba435a111b65430bf5661e1696add19 100644
--- a/src/gpu/vk/GrVkUniformBuffer.h
+++ b/src/gpu/vk/GrVkUniformBuffer.h
@@ -20,7 +20,7 @@ public:
     void* map(const GrVkGpu* gpu) {
         return this->vkMap(gpu);
     }
-    void unmap(const GrVkGpu* gpu) {
+    void unmap(GrVkGpu* gpu) {
         this->vkUnmap(gpu);
     }
     // The output variable createdNewBuffer must be set to true if a new VkBuffer is created in