feat(memory share): send multiple receiver regions

Updates `memory_init_and_send` to allow passing more than one receiver.
Tests for this functionality will be added in the next commit.

Change-Id: I51d92d74f64bfebfa3d49ff6d5066050087b44ef
Signed-off-by: Karl Meakin <karl.meakin@arm.com>
8 files changed