Input: twl6040-vibra - update for device tree support

The twl6040 DT support implementation has been changed from the
originally planned.  None of the child devices going to have
compatible_of property which means that the child devices of twl6040
will be created as traditional MFD devices.  The mfd core driver will
decide (based on the DT blob) to create a device for the twl6040-vibra
or not. If the DT blob has 'vibra' section the device will be created
without pdata.  In this case the vibra driver will reach up to the
parent node to get the needed properties.

With DT booted kernel we no longer be able to link the regulators to
the vibra driver, they can be only linked to the MFD device (probed
via DT). From the vibra driver we ned to use pdev->dev.parent to get
the regulators.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>