feat(plat/versal): add support for SLS mitigation

This patch adds the option HARDEN_SLS_ALL that can be used to enable
the -mharden-sls=all, which mitigates the straight-line speculation
vulnerability. Enable this by adding the option HARDEN_SLS_ALL=1,
default this will be disabled.

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@xilinx.com>
Change-Id: I0d498d9e96903fcb879993ad491949f6f17769b2
2 files changed