mfd: Register the twl6040 child for the ASoC codec unconditionally

The main function of the twl6040 is to provide audio on OMAP4+ platforms.
Since the ASoC codec driver can work without the pdata we can register the
child to load the codec driver whenever the twl6040 MFD driver is loaded.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>