Revert "x86/speculation: Add RSB VM Exit protections"

stable inclusion
from stable-v4.19.266
commit 67b137bf0d9d096f86c8bfa175ca5ab3629369c9
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5GZ2Z


CVE: CVE-2022-29901

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

This reverts commit b6c5011934a15762cd694e36fe74f2f2f93eac9b.

In order to apply IBRS mitigation for Retbleed, PBRSB mitigations must be
reverted and the reapplied, so the backports can look sane.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Suleiman Souhlal <suleiman@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lin Yujun <linyujun809@huawei.com>
Reviewed-by: Zhang Jianhua <chris.zjh@huawei.com>
Reviewed-by: Liao Chang <liaochang1@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>