The inclusion of `umachine` in the list of built-in modules is now done
centrally in py/objmodule.c. Enabling MICROPY_PY_MACHINE will include this
module.
As part of this, all ports now have `umachine` as the core module name
(previously some had only `machine` as the name).
Signed-off-by: Damien George <damien@micropython.org>
fbd47fc46c