The ornamental design for a vehiclemountingplate for a mobile device, as shown and described.
FIG. 1 is a top, rear, right side perspective view of a vehicle mounting plate for a mobile device, showing my new design;
FIG. 2 is a bottom, front, right side perspective view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a right side view thereof.
The left side view is a mirror image of the right side view.
The broken lines in the drawings are included to show portions of the vehicle mounting plate for a mobile devices that form no part of the claimed design.