ARM: dts: qcom: reduce L4B regulator min voltage to 880 mV for sdxlemur

PMX65 LDO 4 (L4B) loads are able to operate successfully with
L4B set to 880 mV.  Therefore, reduce the L4B minimum constraint
voltage to 880 mV.  This allows power to be saved when possible.

Also reduce the minimum voltage voted by USB and PCIe devices to
880 mV to achieve the desired power savings.

Change-Id: Ie9f76e65cac22290e85cfba3b7cf2cea4da3eee3