The SCU controller on the AST2600 SoC has extra registers. Increase
the number of regs of the model and introduce a new field in the class
to customize the MemoryRegion operations depending on the SoC model.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20190925143248.10000-4-clg@kaod.org
[clg: - improved commit log
      - changed vmstate version
      - reworked model integration into new object class
      - included AST2600_HPLL_PARAM value ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>