dmaengine: dw: introduce register mappings for iDMA 32-bit

The integrated DMA (iDMA 32-bit) is Intel designed DMA controller which
mimics Synopsys Designware DMA. This patch appends the register mappings
for the parts which are slightly different to the DesignWare hardware.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>