west: boards: remove arch format option

HWMv2 boards do not support this field

Signed-off-by: Patryk Koscik <[email protected]>

Author: pkoscik

scripts/west_commands/boards.py

@@ -52,8 +52,6 @@ def do_add_parser(self, parser_adder):
             - revision_default: board default revision
             - revisions: list of board revisions
             - qualifiers: board qualifiers (will be empty for legacy boards)
-            - arch: board architecture (deprecated)
-                    (arch is ambiguous for boards described in new hw model)
             - dir: directory that contains the board definition
             - vendor: board vendor
             '''))