mfd: Convert twl6040 to i2c driver, and separate it from twl core

Complete the separation of the twl6040 from the twl core since
it is a separate chip, not part of the twl6030 PMIC.

Make the needed Kconfig changes for the depending drivers at the
same time to avoid breaking the kernel build (vibra, ASoC components).

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonicro.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

sound/soc/omap/Kconfig

@@ -97,7 +97,7 @@ config SND_OMAP_SOC_SDP3430
 
 config SND_OMAP_SOC_OMAP_ABE_TWL6040
 	tristate "SoC Audio support for OMAP boards using ABE and twl6040 codec"
-	depends on TWL4030_CORE && SND_OMAP_SOC && ARCH_OMAP4
+	depends on TWL6040_CORE && SND_OMAP_SOC && ARCH_OMAP4
 	select SND_OMAP_SOC_DMIC
 	select SND_OMAP_SOC_MCPDM
 	select SND_SOC_TWL6040