Merge changes from topic "sgi_to_nrd"

* changes:
  fix(arm): fix comments referencing "SGI platform"
  refactor(sgi): replace references to "SGI"/"sgi" for neoverse_rd
  refactor(sgi): rename "CSS_SGI" macro prefixes to "NRD"
  refactor(sgi): move apis and types to "nrd" prefix
  refactor(sgi): replace build-option prefix to "NRD"
  refactor(sgi): regroup "sgi" and "rdinfra" to "neoverse_rd"