The ornamental design of the floor lamp, as shown and described.
FIG. 1 is a perspective view of a floor lamp showing my new design;
FIG. 2 is a front elevational view thereof, the rear elevational view being a mirror image of that shown;
FIG. 3 is a top plan view thereof; and,
FIG. 4 is a bottom plan view thereof.
The broken-line disclosure in the views is understood to represent a portion of the article in which the claimed design is embodied, but which forms no part of the claimed design.