feat(cm): add explicit context entries for ERRATA_SPECULATIVE_AT

* Currently, "ERRATA_SPECUALTIVE_AT" errata is enabled by default
  for few cores and they need context entries for saving and
  restoring EL1 regs "SCTLR_EL1 and TCR_EL1" registers at all times.

* This prevents the mechanism of decoupling EL1 and EL2 registers,
  as EL3 firmware shouldn't be handling both simultaneously.

* Depending on the build configuration either EL1 or EL2 context
  structures need to included, which would result in saving a good
  amount of context memory.

* In order to achieve this it's essential to have explicit context
  entries for registers supporting "ERRATA_SPECULATIVE_AT".

* This patch adds two context entries under "errata_speculative_at"
  structure to assist this errata and thereby allows decoupling
  EL1 and EL2 context structures.

Change-Id: Ia50626eea8fb64899a2e2d81622adbe07fe77d65
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
8 files changed