ASoC: spdif: Build separate RX and TX objects

Otherwise we fail to link when building as modules due to multiple
init/exit functions.

Reported-by: Fengguang Wu <wfg@linux.intel.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/Makefile

@@ -45,7 +45,8 @@ snd-soc-alc5623-objs := alc5623.o
 snd-soc-alc5632-objs := alc5632.o
 snd-soc-sigmadsp-objs := sigmadsp.o
 snd-soc-sn95031-objs := sn95031.o
-snd-soc-spdif-objs := spdif_transciever.o spdif_receiver.o
+snd-soc-spdif-tx-objs := spdif_transciever.o
+snd-soc-spdif-rx-objs := spdif_receiver.o
 snd-soc-ssm2602-objs := ssm2602.o
 snd-soc-sta32x-objs := sta32x.o
 snd-soc-stac9766-objs := stac9766.o
@@ -159,7 +160,7 @@ obj-$(CONFIG_SND_SOC_RT5631)	+= snd-soc-rt5631.o
 obj-$(CONFIG_SND_SOC_SGTL5000)  += snd-soc-sgtl5000.o
 obj-$(CONFIG_SND_SOC_SIGMADSP)	+= snd-soc-sigmadsp.o
 obj-$(CONFIG_SND_SOC_SN95031)	+=snd-soc-sn95031.o
-obj-$(CONFIG_SND_SOC_SPDIF)	+= snd-soc-spdif.o
+obj-$(CONFIG_SND_SOC_SPDIF)	+= snd-soc-spdif-rx.o snd-soc-spdif-tx.o
 obj-$(CONFIG_SND_SOC_SSM2602)	+= snd-soc-ssm2602.o
 obj-$(CONFIG_SND_SOC_STA32X)   += snd-soc-sta32x.o
 obj-$(CONFIG_SND_SOC_STAC9766)	+= snd-soc-stac9766.o