GitLab

- Apply a53 errata #826319 to revision <= r0p2
- Apply a53 errata #836870 to revision <= r0p3
- Update docs/cpu-specific-build-macros.md for newly added errata build flags

Change-Id: I44918e36b47dca1fa29695b68700ff9bf888865e
Signed-off-by: Jimmy Huang <jimmy.huang@mediatek.com>