mfd: twl-core: Allocate twl_modules dynamically

At boot time we can allocate the twl_modules array dynamically based on the
twl class we are using with devm_kzalloc() instead of the static
twl_modules[] array.

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