The ornamental design for a stand for displaydevice, as shown and described.
1. Stand for display device
1.1: Perspective
1.2: Rear perspective
1.3: Bottom perspective
1.4: Front
1.5: Back
1.6: Left
1.7: Right
1.8: Top
1.9: Bottom
1.10: Enlarged
1.11: Enlarged
1.12: Reference
Reproductions 1.10and 1.11are enlarged views of portions of reproduction 1.1and 1.13, respectively; reproduction 1.12shows the state of use with the display device; the broken lines depict environmental subject matter and form no part of the claimed design.