sound: usb: Fix memory corruption by using correct size

Commit 1efd15d0 ("sound: usb: Adopt new QMI framework related
changes") used wrong structure size while allocating memory
causing random memory corruption. Fix this issue by using correct
structure size.

Change-Id: I07019ad176f4cb6c5b5bcadce3e4df1a3f09219e
Signed-off-by: Mayank Rana <mrana@codeaurora.org>