tests/eas/rfc: Only use the energy meter if the platform supports it
tests/eas/rfc: Only use the energy meter if the platform supports it

EnergyMeter.getInstance() returns None if there is no energy meter for
the platform.  Therefore, env.emeter is None for platforms that don't
have an energy meter and rfc.py fails with an AttributeError when it
tries to do things like cls.env.emeter.reset()

Check that emeter is not None before calling any of its methods.

ARM-software/lisa,arnoldlu/lisa,joelagnel/lisa,credp/lisa,arnoldlu/lisa,ARM-software/lisa,ARM-software/lisa,joelagnel/lisa,bjackman/lisa,mdigiorgio/lisa,credp/lisa,credp/lisa,JaviMerino/lisa,mdigiorgio/lisa,ARM-software/lisa,bjackman/lisa,credp/lisa