The ornamental design for a device mount, as shown and described.
FIG. 1 is a front perspective view of a device mount according to the present invention;
FIG. 2 is a rear perspective view of the device mount;
FIG. 3 is a top view of the device mount;
FIG. 4 is a front view of the device mount;
FIG. 5 is a bottom view of the device mount;
FIG. 6 is a rear view of the device mount;
FIG. 7 is a left side view of the device mount; and,
FIG. 8 is a right side view of the device mount.
The structural features depicted by broken lines have been shown for the purpose of illustrating portions of the device mount that form no part of the claimed design.