ASoC: Samsung: s3c-i2s-v2: Fix build error

Fixes the following error introduced by commit eca3b01d0885
("ASoC: switch over to use snd_soc_register_component() on s3c i2s"):
sound/soc/samsung/s3c-i2s-v2.c:732:32: error: ‘drv’ undeclared (first use in this function)

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>