1. Change camelcase variables to Mbed OS style.
2. Remove functions declarations from the `_alt` header, since they
are now added from the module header regardless whether an alternative
implementation exists.
3. Remove the `extern "c"` declaration from the `_alt` headers.
4. Remove redundant extra lines.
Have the HW accelearation drivers return the platform module
errors about feature unsupported, and hw acceleration failure,
because the moduel specific errors will be removed.
Ron Eldor