ARM: dts: i.MX51: digi-connectcore-som: Update PMIC voltages

This patch updates the PMIC voltages according to the module's
datasheet to match both commercial and industrial variants of the module.

Signed-off-by: Alexander Shiyan <eagle.alexander923@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>