ext4: factor out ext4_fill_raw_inode()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I476C7


CVE: NA
---------------------------

Factor out ext4_fill_raw_inode() from ext4_do_update_inode(), which is
use to fill the in-mem inode contents into the inode table buffer, in
preparation for initializing the exclusive inode buffer without reading
the block in __ext4_get_inode_loc().

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Reviewed-by: Xie Miao <miaoxie@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>