ext4: set lockdep subclass for the ea_inode in ext4_xattr_inode_cache_find()

ext4: set lockdep subclass for the ea_inode in ext4_xattr_inode_cache_find()

If the ea_inode has been pushed out of the inode cache while there is
still a reference in the mb_cache, the lockdep subclass will not be
set on the inode, which can lead to some lockdep false positives.

Fixes: 33d201e0277b ("ext4: fix lockdep warning about recursive inode locking")
Cc: stable@kernel.org
Reported-by: syzbot+d4b971e744b1f5439336@syzkaller.appspotmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230524034951.779531-3-tytso@mit.edu
Signed-off-by: Theodore Ts'o <tytso@mit.edu>