Vulkan: Fix last parameter of viewport driver uniform.

This was introduced in a prior patch.

Bug: angleproject:2717
Change-Id: I8f34377cbb9cbede4237efb1610400a8ed20ae2a
Reviewed-on: https://chromium-review.googlesource.com/1131566
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/vulkan/ContextVk.cpp b/src/libANGLE/renderer/vulkan/ContextVk.cpp
index 88a35a0..f1c1ffe 100644
--- a/src/libANGLE/renderer/vulkan/ContextVk.cpp
+++ b/src/libANGLE/renderer/vulkan/ContextVk.cpp
@@ -891,10 +891,8 @@
 
     // Copy and flush to the device.
     DriverUniforms *driverUniforms = reinterpret_cast<DriverUniforms *>(ptr);
-    driverUniforms->viewport[0]    = static_cast<float>(glViewport.x);
-    driverUniforms->viewport[1]    = static_cast<float>(glViewport.y);
-    driverUniforms->viewport[2]    = static_cast<float>(glViewport.width);
-    driverUniforms->viewport[2]    = static_cast<float>(glViewport.height);
+    *driverUniforms = {static_cast<float>(glViewport.x), static_cast<float>(glViewport.y),
+                       static_cast<float>(glViewport.width), static_cast<float>(glViewport.height)};
 
     ANGLE_TRY(mDriverUniformsBuffer.flush(getDevice()));