Errata/ARM57: Add basic constructs to handle and apply A57 specific erratas

This patch adds basic constructs in the ARMv8 u-boot code
to handle and apply Cortex-A57 specific erratas.

As and example, the framework showcases how erratas 833069, 826974
and 828024 can be handled and applied.

Later on this framework can be extended to include other
erratas.

Signed-off-by: Bhupesh Sharma <bhupesh.sharma@freescale.com>