x86/srso: Add SRSO mitigation for Hygon processors

mainline inclusion
from mainline-v6.6-rc4
commit a5ef7d68
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I94P0E
CVE: CVE-2023-52482

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=a5ef7d68cea1344cf524f04981c2b3f80bedbb0d



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

Add mitigation for the speculative return stack overflow vulnerability
which exists on Hygon processors too.

Signed-off-by: Pu Wen <puwen@hygon.cn>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/tencent_4A14812842F104E93AA722EC939483CEFF05@qq.com


Signed-off-by: Wei Li <liwei391@huawei.com>