af_unix: Remove unix_mkname().

mainline inclusion
from mainline-v5.17-rc1
commit 5c32a3ed
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4OM1C
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5c32a3ed64b4c87ed6d9978074db5f0a54c4cd20



--------------------------------

This patch removes unix_mkname() and postpones calculating a hash to
unix_bind_abstract().  Some BSD stuffs still remain in unix_bind()
though, the next patch packs them into unix_bind_bsd().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Baisong Zhong <zhongbaisong@huawei.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>