Merge changes from topic "lto-fixes" into integration

* changes:
  fix(bl1): add missing `__RW_{START,END}__` symbols
  fix(fvp): don't check MPIDRs with the power controller in BL1
  fix(arm): only expose `arm_bl2_dyn_cfg_init` to BL2
  fix(cm): hide `cm_init_context_by_index` from BL1
  fix(bl1): add missing spinlock dependency