ext4: adjust the layout of the ext4_inode_info structure to save memory

ext4: adjust the layout of the ext4_inode_info structure to save memory

Using pahole, we can see that there are some padding holes
in the current ext4_inode_info structure. Adjusting the
layout of ext4_inode_info can reduce these holes,
resulting in the size of the structure decreasing
from 2424 bytes to 2408 bytes.

Signed-off-by: Junchao Sun <sunjunchao2870@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20240603131524.324224-1-sunjunchao2870@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>