ASoC: SPEAr: Add dependency on dmaengine helpers

I'd be very surprised if anyone has used the Kconfig...

Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/sound/soc/spear/Kconfig b/sound/soc/spear/Kconfig
index 3b7cdad..5b744ed 100644
--- a/sound/soc/spear/Kconfig
+++ b/sound/soc/spear/Kconfig
@@ -27,6 +27,7 @@
 	 Say Y or M if you want to add support for any of the audio
 	 controllers (I2S/SPDIF). You will also need to select
 	 the audio interface codecs to support below.
+	select SND_SOC_DMAENGINE_PCM
 
 config SND_SPEAR_SPDIF_OUT
 	tristate "SPEAr SPDIF Out Device Driver"