platform/x86/intel/ifs: Metadata validation for start_chunk

Add an additional check to validate IFS image metadata field prior to
loading the test image.

If start_chunk is not a multiple of chunks_per_stride error out.

Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Link: https://lore.kernel.org/r/20231005195137.3117166-7-jithu.joseph@intel.com


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>