platform/x86/intel/tpmi: Prevent overflow for cap_offset

cap_offset is a u16 field, so multiplying with TPMI_CAP_OFFSET_UNIT
(which is equal to 1024) to covert to bytes will cause overflow. This
will be a problem once more TPMI features are added.

This field is not used except for calculating pfs->vsec_offset. So, leave
cap_offset field unchanged and multiply with TPMI_CAP_OFFSET_UNIT while
calculating pfs->vsec_offset.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20230622195717.3125088-1-srinivas.pandruvada@linux.intel.comReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/intel/tpmi.c

@@ -356,9 +356,7 @@ static int intel_vsec_tpmi_init(struct auxiliary_device *auxdev)
 		if (!pfs_start)
 			pfs_start = res_start;
 
-		pfs->pfs_header.cap_offset *= TPMI_CAP_OFFSET_UNIT;
-
-		pfs->vsec_offset = pfs_start + pfs->pfs_header.cap_offset;
+		pfs->vsec_offset = pfs_start + pfs->pfs_header.cap_offset * TPMI_CAP_OFFSET_UNIT;
 
 		/*
 		 * Process TPMI_INFO to get PCI device to CPU package ID.