x86/vmscape: Enable the mitigation

jira LE-4704
cve CVE-2025-40300
Rebuild_History Non-Buildable kernel-4.18.0-553.83.1.el8_10
commit-author Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
commit 556c1ad
Empty-Commit: Cherry-Pick Conflicts during history rebuild.
Will be included in final tarball splat. Ref for failed cherry-pick at:
ciq/ciq_backports/kernel-4.18.0-553.83.1.el8_10/556c1ad6.failed

Enable the previously added mitigation for VMscape. Add the cmdline
vmscape={off|ibpb|force} and sysfs reporting.

	Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
	Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
	Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
	Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
(cherry picked from commit 556c1ad)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

# Conflicts:
#	Documentation/admin-guide/kernel-parameters.txt
#	arch/x86/Kconfig
#	arch/x86/kernel/cpu/bugs.c
#	drivers/base/cpu.c
#	include/linux/cpu.h

Author: PlaidCat