ASoC: mediatek: Check SND_SOC_CROS_EC_CODEC dependency

If SND_SOC_MT8183_MT6358_TS3A227E_MAX98357A=y,
below errors can be seen:
sound/soc/codecs/cros_ec_codec.o: In function `send_ec_host_command':
cros_ec_codec.c:(.text+0x534): undefined reference to `cros_ec_cmd_xfer_status'
cros_ec_codec.c:(.text+0x101c): undefined reference to `cros_ec_get_host_event'

This is because it will select SND_SOC_CROS_EC_CODEC
after commit 2cc3cd5f ("ASoC: mediatek: mt8183: support WoV"),
but SND_SOC_CROS_EC_CODEC depends on CROS_EC.

Fixes: 2cc3cd5f ("ASoC: mediatek: mt8183: support WoV")
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Link: https://lore.kernel.org/r/20191023063103.44941-1-maowenan@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/mediatek/Kconfig

@@ -125,7 +125,7 @@ config SND_SOC_MT8183_MT6358_TS3A227E_MAX98357A
 	select SND_SOC_MAX98357A
 	select SND_SOC_BT_SCO
 	select SND_SOC_TS3A227E
-	select SND_SOC_CROS_EC_CODEC
+	select SND_SOC_CROS_EC_CODEC if CROS_EC
 	help
 	  This adds ASoC driver for Mediatek MT8183 boards
 	  with the MT6358 TS3A227E MAX98357A audio codec.