Per schematic, both PU and SOC regulator are supplied from LTC3676 SW1
via VDDSOC_IN rail, add the PU input. Both VDD1P1, VDD2P5 are supplied
from LTC3676 SW2 via VDDHIGH_IN rail, add both inputs.

While no instability or problems are currently observed, the regulators
should be fully described in DT and that description should fully match
the hardware, else this might lead to unforseen issues later. Fix this.

Fixes: 52c7a088 ("ARM: dts: imx6q: Add support for the DHCOM iMX6 SoM and PDK2")
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Ludwig Zenz <lzenz@dh-electronics.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: stable@vger.kernel.org
Reviewed-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>