ext4: fix inode leak in ext4_xattr_inode_create() on an error path

In the Linux kernel, the following vulnerability has been resolved:

ext4: fix inode leak in ext4_xattr_inode_create() on an error path

There is issue as follows when do setxattr with inject fault:

[localhost]# fsck.ext4 -fn /dev/sda
e2fsck 1.46.6-rc1 (12-Sep-2022)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Unattached zero-length inode 15. Clear? no

Unattached inode 15
Connect to /lost+found? no

Pass 5: Checking group summary information

/dev/sda: ********** WARNING: Filesystem still has errors **********

/dev/sda: 15/655360 files (0.0% non-contiguous), 66755/2621440 blocks

This occurs in 'ext4_xattr_inode_create()'. If 'ext4_mark_inode_dirty()'
fails, dropping i_nlink of the inode is needed. Or will lead to inode leak.