Merge changes I907f3862,Ie749ff06,If8da2bb1,I457deb0b into integration

* changes:
  fix(el3-spmc): validate shmem descriptor alignment
  refactor(el3-spmc): avoid using EINVAL
  fix(el3-spmc): avoid descriptor size calc overflow
  fix(el3-spmc): use uint64_t for 64-bit type