refactor: page fault exception handler follows code style

src/userprog/exception.c

@@ -155,6 +155,7 @@ page_fault (struct intr_frame *f)
     {
       if (try_alloc_new_page (fault_addr, thread_current ()->curr_esp))
         return;
+
       f->eip = (void *)f->eax;
       f->eax = 0xffffffff;
       return;