f2fs: avoid opened loop codes in __add_ino_entry

We will keep __add_ino_entry success all the time, for ENOMEM failure
case, we have already handled it by using  __GFP_NOFAIL flag, so we
don't have to use additional opened loop codes here, remove them.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>