swr: Remove Byte Order Mark.

swr: Remove Byte Order Mark.

before:
$ file src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_types.py
src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_types.py: Python script text executable, UTF-8 Unicode (with BOM) text

after:
$ file src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_types.py
src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_types.py: Python script text executable, ASCII text

This patch also fixes this build error.

  File "src/gallium/drivers/swr/rasterizer/codegen/gen_llvm_types.py", line 1

    # Copyright (C) 2014-2018 Intel Corporation.   All Rights Reserved.

    ^

SyntaxError: invalid character in identifier

Fixes: c6e67f5a9373 ("gallium/swr: add OpenSWR rasterizer")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Jan Zielinski <jan.zielinski@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4221>