CVE-2026-74681: usb: misc: usbio: check ibuf_len against rxbuf_len in bulk msg

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

usb: misc: usbio: check ibuflen against rxbuflen in bulk msg

ibuflen is the bulk IN (receive) buffer size, but the EMSGSIZE check in usbiobulkmsg() compares it against txbuflen — the bulk OUT endpoint size. Both are taken independently from different endpoints in usbioprobe(), so the check is wrong when they differ.

Use rxbuflen for the IN direction. This matches the buffer that actually holds the response data.