video/xen-fbfront: Further s/MFN/GFN clean-up

The PV driver xen-fbfront is only dealing with GFN and not MFN. Rename
all the occurence of MFN to GFN.

Also take the opportunity to replace to usage of pfn_to_gfn by
xen_page_to_gfn.
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

drivers/video/fbdev/xen-fbfront.c

@@ -46,7 +46,7 @@ struct xenfb_info {
 	int			nr_pages;
 	int			irq;
 	struct xenfb_page	*page;
-	unsigned long 		*mfns;
+	unsigned long 		*gfns;
 	int			update_wanted; /* XENFB_TYPE_UPDATE wanted */
 	int			feature_resize; /* XENFB_TYPE_RESIZE ok */
 	struct xenfb_resize	resize;		/* protected by resize_lock */
@@ -402,8 +402,8 @@ static int xenfb_probe(struct xenbus_device *dev,
 
 	info->nr_pages = (fb_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
-	info->mfns = vmalloc(sizeof(unsigned long) * info->nr_pages);
-	if (!info->mfns)
+	info->gfns = vmalloc(sizeof(unsigned long) * info->nr_pages);
+	if (!info->gfns)
 		goto error_nomem;
 
 	/* set up shared page */
@@ -530,29 +530,29 @@ static int xenfb_remove(struct xenbus_device *dev)
 		framebuffer_release(info->fb_info);
 	}
 	free_page((unsigned long)info->page);
-	vfree(info->mfns);
+	vfree(info->gfns);
 	vfree(info->fb);
 	kfree(info);
 
 	return 0;
 }
 
-static unsigned long vmalloc_to_mfn(void *address)
+static unsigned long vmalloc_to_gfn(void *address)
 {
-	return pfn_to_gfn(vmalloc_to_pfn(address));
+	return xen_page_to_gfn(vmalloc_to_page(address));
 }
 
 static void xenfb_init_shared_page(struct xenfb_info *info,
 				   struct fb_info *fb_info)
 {
 	int i;
-	int epd = PAGE_SIZE / sizeof(info->mfns[0]);
+	int epd = PAGE_SIZE / sizeof(info->gfns[0]);
 
 	for (i = 0; i < info->nr_pages; i++)
-		info->mfns[i] = vmalloc_to_mfn(info->fb + i * PAGE_SIZE);
+		info->gfns[i] = vmalloc_to_gfn(info->fb + i * PAGE_SIZE);
 
 	for (i = 0; i * epd < info->nr_pages; i++)
-		info->page->pd[i] = vmalloc_to_mfn(&info->mfns[i * epd]);
+		info->page->pd[i] = vmalloc_to_gfn(&info->gfns[i * epd]);
 
 	info->page->width = fb_info->var.xres;
 	info->page->height = fb_info->var.yres;