ARM: 5935/1: [U300] Fix the DMA configuration

This fixes a few bugs in the DMA configuration for the COH 901 318
DMA engine used in U300. It also removes the directional parameter
for each channel: separate DMA engine patches (submitted to the
DMA engine maintainer) switches that mechanism over to using
dynamic configuration of this, to handle bidirectional DMA
channels.

Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>