omap: opp: voltage: Raise voltage up to -5mV under stock and adjust values between each OPP for better stability and battery consumption.

When using too low voltage values it can result in a higher power consumption because the system tries to compensate low power states while being on high frequencies by pulling more energy (Smartreflex) - excuse this explanation, because of my bad ENglish I'm maybe not able to explain it like I want :)