[easy] [PyTorch Edge] Remove double pragma once directive in the gene…

…rated code (pytorch#65620)

Summary:
Pull Request resolved: pytorch#65620

This was bothering me for a while.

ghstack-source-id: 138914860

Test Plan: Sandcastle

Reviewed By: beback4u

Differential Revision: D31162648

fbshipit-source-id: 72c47ea34d40c772bb53da721fcb36365b5dbaf3

tools/lite_interpreter/gen_selected_mobile_ops_header.py

@@ -12,7 +12,7 @@
 }"""
 if_condition_template = CodeTemplate(if_condition_template_str)
 
-selected_kernel_dtypes_h_template_str = """#pragma once
+selected_kernel_dtypes_h_template_str = """
 #include <c10/core/ScalarType.h>
 #include <c10/util/string_view.h>
 #include <c10/macros/Macros.h>