scripts/clang-tools: Convert clang-tidy args to list

Convert list of clang-tidy arguments to a list for ease of adding to
them and extending them as required.

Signed-off-by: Guru Das Srinagesh <quic_gurus@quicinc.com>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>