Fix clang-tidy warnings

* This patch also makes clang-tidy job failed
  when there is any warning in the library code.

Signed-off-by: Viet-Hoa Do <viet-hoa.do@arm.com>

Reviewed-by: Anton Bondarenko <anton.bondarenko@arm.com>
Approved-by: Jakub Sujak <jakub.sujak@arm.com>