security: Remove security_old_inode_init_security()

As the remaining two users reiserfs and ocfs2 switched to
security_inode_init_security(), security_old_inode_init_security() can be
now removed.

Out-of-tree kernel modules should switch to security_inode_init_security()
too.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>