libs/utils/energy: Slightly improve error for missing hwmon channel
libs/utils/energy: Slightly improve error for missing hwmon channel

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