CVE-2017-5753
CVE-2017-5715

Add an IBPB feature check to the speculative control update check after
a microcode reload.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
(backported from commit 073bee2caa42ddde1134cb87c955b4cad7b7d38b)
Signed-off-by: Andy Whitcroft <apw@canonical.com>