ASoC: spdif: set module licence to GPL

Without MODULE_LICENCE("GPL"), when built as a module it will fail
to load because it uses other GPL symbols from kernel.
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/spdif_transciever.c

@@ -21,6 +21,8 @@
 
 #include "spdif_transciever.h"
 
+MODULE_LICENSE("GPL");
+
 #define STUB_RATES	SNDRV_PCM_RATE_8000_96000
 #define STUB_FORMATS	SNDRV_PCM_FMTBIT_S16_LE