ARM: dts: OMAP3: use twl4030 vdd1 regulator for CPU

Define VDD1 regulator in twl4030 DT and mark it as the supply for the
various OMAP34xx/35xx/36xx/37xx platforms (all use TWL4030 variants with
VDD1 supplying the CPU).

NOTE: This currently will use I2C1 bus communication path to set the
voltage in device tree boot. In the legacy non device tree boot, we
continue to use twl-common.c which bypasses I2C1 bus communication path
and uses I2C4 bus path using OMAP voltage libraries. We should
eventually be able to use I2C4 path once we have voltage regulator for
OMAP which is capable of using the voltage controller/voltage processor
IP blocks.

Signed-off-by: Nishanth Menon <nm@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Jon Hunter <jon-hunter@ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Keerthy <j-keerthy@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>