[vulkan] Fix blend constants encoding error

bug: 111137294

Wow :)

Change-Id: I724b0a641b22495897b72db19b2e2771a96689fc
diff --git a/system/vulkan_enc/VkEncoder.h b/system/vulkan_enc/VkEncoder.h
index 16df497..8328b32 100644
--- a/system/vulkan_enc/VkEncoder.h
+++ b/system/vulkan_enc/VkEncoder.h
@@ -473,7 +473,7 @@
         float depthBiasSlopeFactor);
     void vkCmdSetBlendConstants(
     VkCommandBuffer commandBuffer,
-        const float blendConstants);
+        const float blendConstants[4]);
     void vkCmdSetDepthBounds(
     VkCommandBuffer commandBuffer,
         float minDepthBounds,