Add DT nodes for TPS659038 PMIC on DRA7 boards.

It is based on top of:
http://comments.gmane.org/gmane.linux.ports.arm.omap/102459.

Documentation:
- Documentation/devicetree/bindings/mfd/palmas.txt
- Documentation/devicetree/bindings/regulator/palmas-pmic.txt

Boot Tested on DRA7 d1 Board.
Signed-off-by: Keerthy <j-keerthy@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>
[bcousson@baylibre.com: Fix indentation and changelog]
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>