mfd: Fix twl4030 dependencies for audio codec

The codec for Devkit8000 (TWL4030)  was not detected except
when build with CONFIG_SND_SOC_ALL_CODECS.

twl-core.c still uses the CONFIG_TWL4030_CODEC for
twl_has_codec().

In commit 57fe7251f5bfc4332f24479376de48a1e8ca6211
the CONFIG_TWL4030_CODEC was renamed
into CONFIG_MFD_TWL4030_AUDIO, thatswhy the codec
was not detected.

This patch renames the CONFIG_ TWL4030_CODEC into
CONFIG_MFD_TWL4030_AUDIO in twl-core.c.

Signed-off-by: Thomas Weber <weber@corscience.de>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/twl-core.c

@@ -109,7 +109,7 @@
 #define twl_has_watchdog()        false
 #endif
 
-#if defined(CONFIG_TWL4030_CODEC) || defined(CONFIG_TWL4030_CODEC_MODULE) ||\
+#if defined(CONFIG_MFD_TWL4030_AUDIO) || defined(CONFIG_MFD_TWL4030_AUDIO_MODULE) ||\
 	defined(CONFIG_TWL6040_CORE) || defined(CONFIG_TWL6040_CORE_MODULE)
 #define twl_has_codec()	true
 #else