firewire: normalize a variable name

Standardize on  if (err)
                        handle_error;
           and  if (ret < 0)
                        handle_error;

Don't call a variable err if we store values in it which mean success.
Also, offset some return statements by a blank line since this how we do
it in drivers/firewire.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/fw-iso.c b/drivers/firewire/fw-iso.c
index f511d16..2baf100 100644
--- a/drivers/firewire/fw-iso.c
+++ b/drivers/firewire/fw-iso.c
@@ -75,19 +75,21 @@
 	kfree(buffer->pages);
  out:
 	buffer->pages = NULL;
+
 	return -ENOMEM;
 }
 
 int fw_iso_buffer_map(struct fw_iso_buffer *buffer, struct vm_area_struct *vma)
 {
 	unsigned long uaddr;
-	int i, ret;
+	int i, err;
 
 	uaddr = vma->vm_start;
 	for (i = 0; i < buffer->page_count; i++) {
-		ret = vm_insert_page(vma, uaddr, buffer->pages[i]);
-		if (ret)
-			return ret;
+		err = vm_insert_page(vma, uaddr, buffer->pages[i]);
+		if (err)
+			return err;
+
 		uaddr += PAGE_SIZE;
 	}