vulkan: move AllocateCommandBuffers_Bottom

Move it from loader.cpp to driver.cpp and rename it to
driver::AllocateCommandBuffers.  No functional change.

Change-Id: I0abdca7dea128df0b313b90cfb5d5825566fc790
diff --git a/vulkan/libvulkan/code-generator.tmpl b/vulkan/libvulkan/code-generator.tmpl
index 4ec13a0..f3e7dbf 100644
--- a/vulkan/libvulkan/code-generator.tmpl
+++ b/vulkan/libvulkan/code-generator.tmpl
@@ -832,12 +832,10 @@
     {{else}}
         ProcHook::EXTENSION_CORE,
 
-        {{if eq $.Name "vkGetDeviceProcAddr"}}
-          reinterpret_cast<PFN_vkVoidFunction>({{$base}}),
-        {{else if eq $.Name "vkGetDeviceQueue"}}
-          reinterpret_cast<PFN_vkVoidFunction>({{$base}}),
-        {{else}}
+        {{if eq $.Name "vkDestroyDevice"}}
           reinterpret_cast<PFN_vkVoidFunction>({{$base}}_Bottom),
+        {{else}}
+          reinterpret_cast<PFN_vkVoidFunction>({{$base}}),
         {{end}}
         nullptr,
         nullptr,