CVE-2026-93104: RDMA/rvt: Return NULL after port allocation failure

In the Linux kernel, the following vulnerability has been resolved: RDMA/rvt: Return NULL after port allocation failure rvt_alloc_device() deallocates the IB device when its port array cannot be allocated but then returns the pointer to the released allocation. Callers treat any non-NULL value as valid and dereference it, resulting in a use-after-free. Return NULL immediately after deallocation so callers can propagate the allocation failure.