mfd: palmas: Remove code which is not necessary for a device tree boot

Remove code which is not necessary for a device tree boot.

Boot tested on OMAP5-UEVM board.

Signed-off-by: J Keerthy <j-keerthy@ti.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Acked-by: Graeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>