wcnss: Read Voltage and current for regulators from dtsi file

Defining Voltage and current values for IRIS and pronto regulators
in static structure, is keep on increasing as a new target introduce.
To make it more dynamically, reading Current and Voltage values for
IRIS and pronto regulators from dtsi file.

CRs-Fixed: 841574
Change-Id: I3882aa9d78b267da68bdbd7e4f893f263eb48687
Signed-off-by: Anand N Sunkad <asunka@codeaurora.org>