Vulkan: factor base extension name into a function -- continue

Bug: 134185757
Test: ./scripts/code_generator.py && build
Change-Id: I5d1e604a4c70e009605cb6f5a28d4214be796dda
diff --git a/vulkan/scripts/generator_common.py b/vulkan/scripts/generator_common.py
index 5bfa9ec..670ba66 100644
--- a/vulkan/scripts/generator_common.py
+++ b/vulkan/scripts/generator_common.py
@@ -286,7 +286,7 @@
   """
   f.write(indent(1))
   if name in extension_dict:
-    f.write('INIT_PROC_EXT(' + extension_dict[name][3:] + ', ')
+    f.write('INIT_PROC_EXT(' + base_ext_name(extension_dict[name]) + ', ')
   else:
     f.write('INIT_PROC(')