This patch adds NXP i.MX8 SoCs' build info SIP support for easy debug.
With this function enabled, TF-A's commit hash can be showed in u-boot
debug console when booting up, when there is any issue which could be
related to TF-A, users can use the commit hash value to easily identify
which commit introduces the issue.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>