[GPU] Change texture load cbuffer to push constants

Simplify the code, eliminating the need for supporting requesting cbuffers
for anything other than guest draw command execution.

src/xenia/gpu/vulkan/vulkan_command_processor.h

@@ -50,7 +50,6 @@ class VulkanCommandProcessor : public CommandProcessor {
  public:
   // Single-descriptor layouts for use within a single frame.
   enum class SingleTransientDescriptorLayout {
-    kUniformBufferCompute,
     kStorageBufferCompute,
     kCount,
   };
@@ -217,16 +216,6 @@ class VulkanCommandProcessor : public CommandProcessor {
   // A frame must be open.
   VkDescriptorSet AllocateSingleTransientDescriptor(
       SingleTransientDescriptorLayout transient_descriptor_layout);
-  // Allocates a descriptor, space in the uniform buffer pool, and fills the
-  // VkWriteDescriptorSet structure and VkDescriptorBufferInfo referenced by it.
-  // Returns null in case of failure.
-  uint8_t* WriteTransientUniformBufferBinding(
-      size_t size, SingleTransientDescriptorLayout transient_descriptor_layout,
-      VkDescriptorBufferInfo& descriptor_buffer_info_out,
-      VkWriteDescriptorSet& write_descriptor_set_out);
-  uint8_t* WriteTransientUniformBufferBinding(
-      size_t size, SingleTransientDescriptorLayout transient_descriptor_layout,
-      VkDescriptorSet& descriptor_set_out);
 
   // The returned reference is valid until a cache clear.
   VkDescriptorSetLayout GetTextureDescriptorSetLayout(bool is_vertex,