ARM: SPEAr13xx: Pass DW DMAC platform data from DT

This patch adds dw_dmac's platform data to DT node. It also creates slave info
node for SPEAr13xx, for the devices which were using dw_dmac.

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