CVE-2024-38546 drm: vc4: Fix possible null pointer dereference

In the Linux kernel, the following vulnerability has been resolved: drm: vc4: Fix possible null pointer dereference In vc4hdmiaudioinit ofgetaddress may return NULL which is later dereferenced. Fix this bug by adding NULL check. Found by Linux Verification Center linuxtesting.org with SVACE...