The ornamental design for a cleaning mop, as shown and described.
1. Cleaning mop
1.1 : Front
1.2 : Back
1.3 : Left
1.4 : Right
1.5 : Bottom
The design is a cleaning implement with a sponge mop and foam protection surrounding the bottom of the pole; protection is sought for the sponge mop and foam protected part of the pole; protection is not sought for the rest of the pole which is not foam protected.