xfs: Remove unused function xrep_dir_self_parent

The function are defined in the dir_repair.c file, but not called
elsewhere, so delete the unused function.

fs/xfs/scrub/dir_repair.c:186:1: warning: unused function 'xrep_dir_self_parent'.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=8867


Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>