The ornamental design of a lightingdevice, as shown and described.
FIG. 1 is a front perspective view of a lighting device in accordance with the present invention;
FIG. 2 is a front side view thereof;
FIG. 3 is a right side view thereof, a left side view being a mirror image thereof;
FIG. 4 is a rear side view thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The lighting device is not limited to the scale shown herein. The broken lines of the Figures are for illustrative purposes only and form no part of the claimed design.