The ornamental design for a cheekpad for helmet, as shown and described.
FIG. 1 is a rear perspective view of a cheek pad for helmet showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a right side view thereof; and,
FIG. 7 is a left side view thereof.
The broken lines illustrate portions of the cheek pad for helmet and form no part of the claimed design. The dash-dotted lines denote the boundary of the claim and form no part of the claimed design.