CVE-2026-31544 firmware: arm_scmi: Fix NULL dereference on notify error path

In the Linux kernel, the following vulnerability has been resolved: firmware: armscmi: Fix NULL dereference on notify error path Since commit b5daf93b809d1 "firmware: armscmi: Avoid notifier registration for unsupported events" the call chains leading to the helper scmieventhandlergetops expect a...