feat(versal): get the handoff params using IPI

Use the IPI command GET_HANDOFF_PARAM to get the TF-A handoff
params, rather than using the PLM's PPU RAM area. With this
approach this resolves the issue when XPPU is enabled.

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@xilinx.com>
Reviewed-by: Michal Simek <michal.simek@amd.com>
Change-Id: I6828c391ad696d2d36e994684aa21b023711ba2d