fbdev: vga16fb: Request memory region

This patch reserve and release VGA memory region.

This align with Documentation/drm/todo.rst
"Request memory regions in all fbdev drivers"

I've tested with 32bits kernel and qemu.

Signed-off-by: Javier Garcia <[e-mail]>
Signed-off-by: Helge Deller <[e-mail]>

drivers/video/fbdev/vga16fb.c

···
 		return ret;
 
 	dev_dbg(&dev->dev, "initializing\n");
+	if (!request_mem_region(vga16fb_fix.smem_start, vga16fb_fix.smem_len,
+				"vga16b")) {
+		dev_err(&dev->dev, "cannot reserve video memory at 0x%lx\n",
+		       vga16fb_fix.smem_start);
+	}
 	info = framebuffer_alloc(sizeof(struct vga16fb_par), &dev->dev);
 
 	if (!info) {
···
  err_ioremap:
 	framebuffer_release(info);
  err_fb_alloc:
+	release_mem_region(vga16fb_fix.smem_start,
+		    vga16fb_fix.smem_len);
 	return ret;
 }
 
···
 
 	if (info)
 		unregister_framebuffer(info);
+	release_mem_region(vga16fb_fix.smem_start,
+		    vga16fb_fix.smem_len);
 }
 
 static const struct platform_device_id vga16fb_driver_id_table[] = {