ASoC: dwc: add DMA handshake control

DMA mode uses hardware handshake signals. DMACR register is used to enable
the DMA Controller interface operation. So add DMA enable/disable to
i2s_start()/i2s_stop() functions if using DMA mode.

Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Link: https://lore.kernel.org/r/20230613191910.725049-1-fido_max@inbox.ru


Signed-off-by: Mark Brown <broonie@kernel.org>