ASoC: sunxi: compatibility for sun6i to SPDIF

The A31 SoC uses the same SPDIF block as found in earlier SoCs, but its
reset is controlled via a separate reset controller.

The DMA also complains when the maxburst is set to 4 so it's been adjusted
to 8 which suites both the older and newer SoCs.

Signed-off-by: Marcus Cooper <codekipper@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>