platform/x86/intel/ifs: Store IFS generation number

platform/x86/intel/ifs: Store IFS generation number

IFS generation number is reported via MSR_INTEGRITY_CAPS.  As IFS
support gets added to newer CPUs, some differences are expected during
IFS image loading and test flows.

Define MSR bitmasks to extract and store the generation in driver data,
so that driver can modify its MSR interaction appropriately.

Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Link: https://lore.kernel.org/r/20231005195137.3117166-2-jithu.joseph@intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>