I claim the ornamental design for a lighting device, as shown and described.
FIG. 1 is a perspective view of the lighting device showing my new design with the adjustable portions in a first position, as viewed from the top and one side;
FIG. 2 is a perspective view of the lighting device showing the adjustable portions in an alternate position, as viewed from the top and one side;
FIG. 3 is a top plan view of the lighting device of FIG. 1;
FIG. 4 is a bottom plan view of the lighting device of FIG. 1;
FIG. 5 is a front elevation view of the lighting device of FIG. 1;
FIG. 6 is a rear elevation view of the lighting device of FIG. 1;
FIG. 7 is a first side elevation view of the lighting device of FIG. 1; and,
FIG. 8 is a second side elevation view of the lighting device of FIG. 1.
The details shown in broken lines illustrate portions of the lighting device that form no part of the claimed design.