power: supply: ab8500: cleanup with list_first_entry_or_null()

The combo of list_empty() check and return list_first_entry()
can be replaced with list_first_entry_or_null().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/supply/ab8500_fg.c

@@ -245,13 +245,8 @@ static LIST_HEAD(ab8500_fg_list);
  */
 struct ab8500_fg *ab8500_fg_get(void)
 {
-	struct ab8500_fg *fg;
-
-	if (list_empty(&ab8500_fg_list))
-		return NULL;
-
-	fg = list_first_entry(&ab8500_fg_list, struct ab8500_fg, node);
-	return fg;
+	return list_first_entry_or_null(&ab8500_fg_list, struct ab8500_fg,
+					node);
 }
 
 /* Main battery properties */