mfd: twl4030-audio: Clean up MODULE_* and platform_driver part

Place the MODULE_* lines in the same block and add MODULE_DESCRIPTION.
Rearange the platform_driver structure at the same time.

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