fbdev: fsl-diu-fb: Fix sparse warning due to virt_to_phys() prototype change

Explicitly cast __iomem pointer to const void* with __force to fix the
following warning:

   incorrect type in argument 1 (different address spaces)
      expected void const volatile *address
      got char [noderef] __iomem *screen_base
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311161120.BgyxTBMQ-lkp@intel.com/Signed-off-by: Helge Deller <deller@gmx.de>

drivers/video/fbdev/fsl-diu-fb.c

@@ -877,7 +877,7 @@ static int map_video_memory(struct fb_info *info)
 	}
 	mutex_lock(&info->mm_lock);
 	info->screen_base = p;
-	info->fix.smem_start = virt_to_phys(info->screen_base);
+	info->fix.smem_start = virt_to_phys((__force const void *)info->screen_base);
 	info->fix.smem_len = smem_len;
 	mutex_unlock(&info->mm_lock);
 	info->screen_size = info->fix.smem_len;