ASoC: ti: fix SND_SOC_DM365_VOICE_CODEC dependencies

SND_SOC_DM365_VOICE_CODEC is a 'bool' option in a choice statement,
meaning it cannot be set to =m, but it selects two other drivers
that we may want to be loadable modules after all:

WARNING: unmet direct dependencies detected for SND_SOC_CQ0093VC
  Depends on [m]: SOUND [=m] && !UML && SND [=m] && SND_SOC [=m]
  Selected by [y]:
  - SND_SOC_DM365_VOICE_CODEC [=y] && <choice>
  Selected by [m]:
  - SND_SOC_ALL_CODECS [=m] && SOUND [=m] && !UML && SND [=m] && SND_SOC [=m] && COMPILE_TEST [=y]

Add an intermediate symbol that sets SND_SOC_CQ0093VC and
MFD_DAVINCI_VOICECODEC to =m if SND_SOC=m.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20190920075046.3210393-1-arnd@arndb.deSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/ti/Kconfig

@@ -200,11 +200,18 @@ config SND_SOC_DM365_AIC3X_CODEC
 
 config SND_SOC_DM365_VOICE_CODEC
 	bool "Voice Codec - CQ93VC"
-	select MFD_DAVINCI_VOICECODEC
-	select SND_SOC_CQ0093VC
 	help
 	  Say Y if you want to add support for SoC On-chip voice codec
 endchoice
 
+config SND_SOC_DM365_VOICE_CODEC_MODULE
+	def_tristate y
+	depends on SND_SOC_DM365_VOICE_CODEC && SND_SOC
+	select MFD_DAVINCI_VOICECODEC
+	select SND_SOC_CQ0093VC
+	help
+	  The is an internal symbol needed to ensure that the codec
+	  and MFD driver can be built as loadable modules if necessary.
+
 endmenu