platform/x86: ISST: fix use-after-free in tpmi_sst_dev_remove()

In tpmi_sst_dev_remove(), tpmi_sst is dereferenced after being freed.
Fix this by reordering the kfree() post the dereference.

Fixes: 9d1d3626 ("platform/x86: ISST: Support partitioned systems")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20240517144946.289615-1-harshit.m.mogalapalli@oracle.comSigned-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c

@@ -1610,8 +1610,8 @@ void tpmi_sst_dev_remove(struct auxiliary_device *auxdev)
 	tpmi_sst->partition_mask_current &= ~BIT(plat_info->partition);
 	/* Free the package instance when the all partitions are removed */
 	if (!tpmi_sst->partition_mask_current) {
-		kfree(tpmi_sst);
 		isst_common.sst_inst[tpmi_sst->package_id] = NULL;
+		kfree(tpmi_sst);
 	}
 	mutex_unlock(&isst_tpmi_dev_lock);
 }