feat(cm): test integrity of el1_ctx registers

* This patch adds support to tsp (BL32) Image, to exercise
  EL1_context registers at S-EL1.

* Adds a SMC function ID "MODIFY_EL1_CTX" to handle EL1_CTX
  registers at S-EL1 and overwrite them.

Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: Id4f2b3b748f7bc9e6c9d72a2f03d50aefbfb61cb
6 files changed