The ornamental design for a walllamp, as shown and described.
FIG. 1 is a front perspective view of a wall lamp showing my new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a right side elevational view thereof, the left side elevational view being substantially a mirror image;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The portions of the drawings provided by broken line are intended to reflect environment and do not form a part of the indicated embodiment of my design.