I claim the ornamental design for a lock dial, as shown and described.
FIG. 1 is a perspective view of lock dial showing my new design, shown in its environmental use;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a perspective view thereof, shown in another environmental use;
FIG. 4 is another perspective view thereof;
FIG. 5 is a top plan view of FIG. 4; and,
FIG. 6 is a front elevational view of FIG. 4.
The broken lines environment is for illustrative purposes only. The broken lines adjacent to the shaded area form the boundary of the claimed design. None of the broken lines form part of the claimed design.