xfs: add selinux labels to whiteout inodes

We got a report that "renameat2() with flags=RENAME_WHITEOUT doesn't
apply an SELinux label on xfs" as it does on other filesystems
(for example, ext4 and tmpfs.)  While I'm not quite sure how labels
may interact w/ whiteout files, leaving them as unlabeled seems
inconsistent at best. Now that xfs_init_security is not static,
rename it to xfs_inode_init_security per dchinner's suggestion.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>