dma: coh901318: skip hard-coded addresses

Remove hard-coded target addresses altogether. Skip the prefix
"runtime_*" from the variables, since all of these are now
runtime and their names are unique enough already.

Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>