CVE-2026-98806: octeontx2-pf: Fix aura BPID assignment when CONFIG_DCB is enabled

In the Linux kernel, the following vulnerability has been resolved:

octeontx2-pf: Fix aura BPID assignment when CONFIGDCB is enabled

Previously, BPID assignment under CONFIGDCB assumed queuetopfcmap was always initialized. For SDP VFs this leads to invalid memory access as it was not initialized.

This patch adds a NULL check for queuetopfcmap before dereferencing it. Also, simplifies the logic by always assigning a default BPID first, then conditionally overriding it if CONFIGDCB is enabled and the map exists.