The ornamental design for a deviceholder, substantially as shown and described.
FIG. 1 is a front perspective view of a device holder showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines showing a zipper pull tab and zipper teeth, and the broken lines shown around the zipper in the figures are shown to illustrate environment only and form no part of the claimed design.