[media] videobuf2-vmalloc: fix sparse warning

Fix this warning:

drivers/media/v4l2-core/videobuf2-vmalloc.c:98:28: warning: incorrect type in assignment (different address spaces)
drivers/media/v4l2-core/videobuf2-vmalloc.c:158:28: warning: incorrect type in argument 1 (different address spaces)

The warning is correct, but we have no other choice here to forcibly cast.
At least it is now explicit that such a cast is needed.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/v4l2-core/videobuf2-vmalloc.c

@@ -95,7 +95,7 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 		if (vb2_get_contig_userptr(vaddr, size, &vma, &physp))
 			goto fail_pages_array_alloc;
 		buf->vma = vma;
-		buf->vaddr = ioremap_nocache(physp, size);
+		buf->vaddr = (__force void *)ioremap_nocache(physp, size);
 		if (!buf->vaddr)
 			goto fail_pages_array_alloc;
 	} else {
@@ -155,7 +155,7 @@ static void vb2_vmalloc_put_userptr(void *buf_priv)
 		kfree(buf->pages);
 	} else {
 		vb2_put_vma(buf->vma);
-		iounmap(buf->vaddr);
+		iounmap((__force void __iomem *)buf->vaddr);
 	}
 	kfree(buf);
 }