This fixes the expression in the driver to do the correct thing,
not that I think anyone would send SND_* without EV_SND.

Thanks to Roel Kluin <roel.kluin@gmail.com> for noticing.
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>