Perform additional validation prior to loading IFS image.

Error out if the size of the file being loaded doesn't match the size
specified in the header.
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/20231005195137.3117166-6-jithu.joseph@intel.comSigned-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>