samples: drivers: peci: Exclude MEC172x EVB from test

PECI bus sample requires a controller and a target
Intel system(PECI controller) + Embedded controller(PECI target),
where EC HW can be add-on card (mec172xmodular) or onboard EC.

MEC172x EVB is not intended to be connected hence excluding
the platform.

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