The ornamental design for a walllamp, as shown and described.
FIG. 1 is a front perspective view of a wall lamp, showing my design.
FIG. 2 is a front elevation view thereof.
FIG. 3 is a rear elevation view thereof.
FIG. 4 is a left side elevation view thereof.
FIG. 5 is a right side elevation view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines shown on the rear of the article represent portions of the wall lamp that form no part of the claimed design. The broken lines on the bottom of the article represent the boundary of the claimed design, and form no part of the claimed design.