imx8mp_evk: Increase VDD_ARM to 0.95v Overdrive voltage

imx8mp_evk: Increase VDD_ARM to 0.95v Overdrive voltage

There is a frequency/timing limitation for SOC and ARM, if SOC is OD
voltage/OD freq, then ARM can't run at ND voltage/1.2Ghz, it may have
timing risk from SOC to ARM.

Current VDD_SOC is set to 0.95v OD voltage in SPL, and kernel will
increase bus clocks to OD frequency before it increases ARM voltage.
So to conform to the limitation, we'd better increases VDD_ARM to OD
voltage in SPL.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>