ASoC: max98988: make it selectable

Currently the driver will build only if SND_SOC_ALL_CODECS is set.
Adding a Kconfig menu description to build the driver standalone.
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/Kconfig

@@ -640,7 +640,7 @@ config SND_SOC_LM49453
 	tristate
 
 config SND_SOC_MAX98088
-       tristate
+	tristate "Maxim MAX98088/9 Low-Power, Stereo Audio Codec"
 
 config SND_SOC_MAX98090
        tristate