drm/msm/dpu: fix mismatch in function argument.

Fix the sparse error. the dpu_rm_init declaration is not consistent
with the implement.
Signed-off-by: Nzhong jiang <zhongjiang@huawei.com>
[robclark un-typo'd subject line]
Signed-off-by: NRob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/disp/dpu1/dpu_rm.h

@@ -105,7 +105,7 @@ struct dpu_rm_hw_iter {
  */
 int dpu_rm_init(struct dpu_rm *rm,
 		struct dpu_mdss_cfg *cat,
-		void *mmio,
+		void __iomem *mmio,
 		struct drm_device *dev);
 
 /**