ARM: dts: twl6030: Move common configuration for OMAP4 boards in a separate dtsi file

The OMAP4 SoC family uses specially-designed PMIC (power management IC)
companion chip for power management needs: TWL6030/TWL6032.
Therefore there is a typical connection of PMIC to OMAP4 so we can
move it into separate .dtsi file and do not duplicate over
board-specific files.

Tested on OMAP4 SDP board and Pandaboard ES2.

Signed-off-by: Ruslan Bilovol <ruslan.bilovol@ti.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>