cve-check.bbclass: Fix override syntax

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

meta-oniro-staging/classes/cve-check.bbclass

@@ -176,7 +176,7 @@ python cve_check_write_rootfs_manifest () {
             bb.plain("Image CVE status stored in: %s" % manifest_name)
 }
 
-ROOTFS_POSTPROCESS_COMMAND_prepend = "${@'cve_check_write_rootfs_manifest; ' if d.getVar('CVE_CHECK_CREATE_MANIFEST') == '1' else ''}"
+ROOTFS_POSTPROCESS_COMMAND:prepend = "${@'cve_check_write_rootfs_manifest; ' if d.getVar('CVE_CHECK_CREATE_MANIFEST') == '1' else ''}"
 do_rootfs[recrdeptask] += "${@'do_cve_check' if d.getVar('CVE_CHECK_CREATE_MANIFEST') == '1' else ''}"
 
 def save_status_file(d, tmp_file, logpath, summary_name, timestamp):