dmaengine/dw_dmac: allow src/dst masters to be configured at runtime

Some platforms have flexible mastering capabilities and this needs
to be selected at runtime. If the platform has specified private
data in the form of the dw_dma_slave then fetch the source and
destination masters from here. If this isn't present, default to
the previous of 0 and 1.

v2: cleanup whitespace

Acked-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Signed-off-by: Jamie Iles <jamie.iles@picochip.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/include/linux/dw_dmac.h b/include/linux/dw_dmac.h
index c8aad71..8014eb8 100644
--- a/include/linux/dw_dmac.h
+++ b/include/linux/dw_dmac.h
@@ -52,6 +52,8 @@
 	enum dw_dma_slave_width	reg_width;
 	u32			cfg_hi;
 	u32			cfg_lo;
+	int			src_master;
+	int			dst_master;
 };
 
 /* Platform-configurable bits in CFG_HI */