powerpc/83xx/km: MV88e6122 errata fix for 1.9V

Errata Fix: 1.9V Output from Internal 1.8V Regulator, acc.
MV-S300889-00D.pdf , clause 4.5

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>