fix(versal): enable a72 erratum 859971 and 1319367

TF-A is reporting that above two erratum are missing to be enabled that's
why enable them by default.

For futher information please refer to
https://developer.arm.com/documentation/epm012079/11/



where
859971 is "Speculative instruction prefetch to Execute-never (XN) memory
could cause deadlock or data integrity issue" and
1319367 is "Speculative AT instruction using out-of-context translation
regime could cause subsequent request to generate an incorrect
translation".

Change-Id: I408706713a169e53db63ac5657751b0b003e646d
Signed-off-by: Michal Simek <michal.simek@amd.com>