mcb: fix error handling in mcb_alloc_bus()

mcb: fix error handling in mcb_alloc_bus()

This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven.
This ID is fixed in Linux Kernel version v5.4.150 by commit 7751f609eadf36b1f53712bae430019c53a16eb0, it was introduced in version v4.7 by commit 5d9e2ab9fea4cdf0a2522f5cbed2e7fbb220d757. For more details please see the references link.