ASoC: rt5616: allow to build with CONFIG_SND_SOC_RT5616

This patch fixes that hasn't built the rt5616 driver with
'CONFIG_SND_SOC_RT5616=y' in .config.

The tristate is the prompt on the 'make menuconfig',
in other words, that can't show the prompt and select it
if we don't say what's the tristate.
Signed-off-by: NCaesar Wang <wxt@rock-chips.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/codecs/Kconfig

@@ -596,7 +596,7 @@ config SND_SOC_RT298
 	depends on I2C
 
 config SND_SOC_RT5616
-	tristate
+	tristate "Realtek RT5616 CODEC"
 
 config SND_SOC_RT5631
 	tristate "Realtek ALC5631/RT5631 CODEC"