feat(el3-spmc): add support to handle power mgmt calls for s-el0 sp

Add support to setup S-EL0 SP context during power management power on
procedure. In case of power on, initialise the context data structure
for the secure world on the current CPU.
The S-EL0 SP does not support power message. Add the check to make
sure that it does not subscribe to any power messages.

Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Signed-off-by: Nishant Sharma <nishant.sharma@arm.com>
Change-Id: Ic9cf98cd15b6ee5d86d071a52bc0973677049df3
2 files changed