feat: add spm_deactivate_interrupt helper function

This ABI is needed by SP to perform End-Of-Interrupt sequence i.e.,
priority drop and de-activation on its behalf by SPM.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: I6c5403b4591589f29da7b77f69f422b9eb386efd
2 files changed