board/freescale/vid: Add correction for ltc3882 read error.

board/freescale/vid: Add correction for ltc3882 read error.

Voltage regulator LTC3882 device has 0.5% voltage read error.
So for NXP SoC devices this generally equates to 2mV

Update set_voltage_to_LTC for below:
1.Add coorection of upto 2mV in voltage comparison
  to take care of voltage read error of voltage regulator
2.Add loop max count kept as 100 to avoid infinte loop.

Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>