intel_th: Don't leak module refcount on failure to activate

Output 'activation' may fail for the reasons of the output driver,
for example, if msc's buffer is not allocated. We forget, however,
to drop the module reference in this case. So each attempt at
activation in this case leaks a reference, preventing the module
from ever unloading.

This patch adds the missing module_put() in the activation error
path.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: stable@vger.kernel.org # v4.8+