boards: arm: mec1501modular: Correct I2C bus configurations

MEC1501modular doesn't expose same I2C instances than MEC15xxevb,
additionally this causes undesired reconfiguration of pins with
other function when card is mated with a platform that complies
with MECC specification.

Signed-off-by: Jose Alberto Meza <jose.a.meza.arellano@intel.com>