These removed ones are either unused by MicroPython or provided by osapi.h
in the SDK. In particular ets_delay_us() has different signatures for
different versions of the SDK, so best to let it provide the declaration.
Fixes issue #8095.
Signed-off-by: Damien George <damien@micropython.org>
In the vendor SDK 2.1.0, some of the functions which previously didn't
have prototypes, finally acquired them. Change prototypes on our side
to match those in vendor headers, to avoid warnings-as-errors.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
