dmaengine: dw: keep copy of custom slave config in dwc

It seems we need to extend custom slave configuration by one more member to
support Intel Quart UART. It becomes a burden to manage all members of struct
dw_dma_slave one-by-one.

Replace the set of fields by embedding struct dw_dma_slave into struct
dw_dma_chan.

Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/dma/dw/regs.h b/drivers/dma/dw/regs.h
index 4b7bd78..f65dd10 100644
--- a/drivers/dma/dw/regs.h
+++ b/drivers/dma/dw/regs.h
@@ -245,10 +245,7 @@
 	bool			nollp;
 
 	/* custom slave configuration */
-	u8			src_id;
-	u8			dst_id;
-	u8			m_master;
-	u8			p_master;
+	struct dw_dma_slave	dws;
 
 	/* configuration passed via .device_config */
 	struct dma_slave_config dma_sconfig;