ARM: common: edma: Internal API to use pointer to 'struct edma'

Merge the iomem into the 'struct edma' and change the internal (static)
functions to use pointer to the edma_cc instead of the ctlr number.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>