dmaengine/dw_dmac: Fix dw_dmac user drivers to adapt to slave_config changes

There are few existing user drivers of dw_dmac. They will break as soon as we
remove unused fields from struct dw_dma_slave. This patch focuses to fix these
user drivers to use dma_slave_config() routine.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>