SR: Custom SR Tuning v1 - supports MPU, IVA, and CORE

Override kernel default VDDMIN via sysfs (debug fs).
/sys/kernel/debug/smartreflex/sr_*/vmin

Signed-off-by: Dan Trifan <jimsth@gmail.com>
 Custom SR Tuning V2: allow SR to calibrate high voltages

For MPU only, should have zero effect on IVA and CORE

Signed-off-by: Dan Trifan <jimsth@gmail.com>