Emma Ballantyne authored Feb 26, 2025 and Leandro Belli committed Mar 27, 2025

Rename arch_helpers.h to arch_interrupt.h, as well as adding a defintion
of arch_interrupt_init to fwk_arch.h.

Signed-off-by: Emma Ballantyne <emma.ballantyne2@arm.com>
Signed-off-by: James Chesterman <james.chesterman@arm.com>