[media] media: s5p-mfc: fix sparse warnings

Commits a0f10c131cc49d7d84394beb7903e1f246331224 and
6c9fe765360efa97c63b89af685b620baf5e0012 ("media: s5p-mfc: fix broken
pointer cast on 64bit arch") fixed issue with lossy cast on 64-bit
architectures. However it also removed __iomem attribute from that cast.
This leads to sparse warnings. This patch fixes those warnings by adding
__iomem cast in case of v6+ code version and replacing readl/writel by
simple u32 load/store operations in case of v5 code (which is called on
system memory allocated by dma_alloc_coherent() instead of io registers).

Reported-by: Hans Verkuil <[e-mail]>
Signed-off-by: Marek Szyprowski <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/s5p-mfc/s5p_mfc_opr_v5.c

···
 static void s5p_mfc_write_info_v5(struct s5p_mfc_ctx *ctx, unsigned int data,
 			unsigned int ofs)
 {
-	writel(data, (void *)(ctx->shm.virt + ofs));
+	*(u32 *)(ctx->shm.virt + ofs) = data;
 	wmb();
 }
 
···
 				unsigned long ofs)
 {
 	rmb();
-	return readl((void *)(ctx->shm.virt + ofs));
+	return *(u32 *)(ctx->shm.virt + ofs);
 }
 
 static void s5p_mfc_dec_calc_dpb_size_v5(struct s5p_mfc_ctx *ctx)

drivers/media/platform/s5p-mfc/s5p_mfc_opr_v6.c

···
 		unsigned int ofs)
 {
 	s5p_mfc_clock_on();
-	writel(data, (void *)((unsigned long)ofs));
+	writel(data, (void __iomem *)((unsigned long)ofs));
 	s5p_mfc_clock_off();
 }
 
···
 	int ret;
 
 	s5p_mfc_clock_on();
-	ret = readl((void *)ofs);
+	ret = readl((void __iomem *)ofs);
 	s5p_mfc_clock_off();
 
 	return ret;