Defending champions Cameroon edged Zambia 2-1 and Ghana lost 1-0 to Namibia on Sunday in warm-up matches for the Africa Cup of Nations, which kicks off on June 21 in Egypt. Playing their first friendly ahead of the 24-nation tournament, Cameroon built a two-goal lead through Paul-Georges Ntep and Joel Tagueu in Madrid. Mwape Musonda, the leading scorer this season …