Add entries for VDD_ARM_CAP and VDD_SOC_CAP voltages for 198MHz according
to the imx6sx datahseet:
http://cache.nxp.com/files/32bit/doc/data_sheet/IMX6SXIEC.pdf
(a 25mV offset is added to the minimum allowed values for safety).
These values also match the ones from the NXP kernel.