iec61937: set iec958 boolean before use it

During prepare alsa->iec958  is tested before set.
Effect is that alsa device is not opened in iec958 mode,
so AES value are not transmitted to alsa driver.

https://bugzilla.gnome.org/show_bug.cgi?id=757258

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
1 file changed