ARM: SPEAr13xx: Pass generic DW DMAC platform data from DT

This replaces an earlier patch from Viresh Kumar to move
the spear platform over to the generic DMA binding. This
version is now based on the merged multiplatform capable
spear platform, rather than the separate spear13xx/3xx/6xx
directories.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Shiraz Hashim <shiraz.hashim@st.com>
Cc: spear-devel@list.st.com