ALSA: qc_audio_offload: avoid leaking xfer_buf allocation

ALSA: qc_audio_offload: avoid leaking xfer_buf allocation

The info->xfer_buf_cpu member is set to a NULL value because the
allocation happens in a different function and is only assigned
to the function argument but never passed back.

Pass it by reference instead to have a handle that can actually be
freed by the final usb_free_coherent() call.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20250513123442.159936-3-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>