remoteproc/mediatek: fix sparse errors on dma_alloc and dma_free

remoteproc/mediatek: fix sparse errors on dma_alloc and dma_free

Fixes the following sparse errors on dma_alloc_coherent() and
dma_free_coherent().

On drivers/remoteproc/mtk_scp.c:559:23:
warning: incorrect type in assignment (different address spaces)
   expected void [noderef] __iomem *cpu_addr
   got void *

On drivers/remoteproc/mtk_scp.c:572:56:
warning: incorrect type in argument 3 (different address spaces)
   expected void *cpu_addr
   got void [noderef] __iomem *cpu_addr

The cpu_addr is not a __iomem address.  Removes the marker.

Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20201116082537.3287009-3-tzungbi@google.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>