feat(bl31): add placeholder activator implementation for LFA

Introduce the BL31 component's activator structure with stub
implementations for the 'prime' and 'activate' callbacks.

Both callbacks currently return LFA_WRONG_STATE, indicating that
activation is not supported or allowed from BL31 in this context.

This activator is registered via get_bl31_activator(), allowing
the platform layer to wire it into the LFA framework.

Change-Id: I4279996b218d558a45cd99d5840f0e9f8ee97f90
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
2 files changed