The ornamental design for a ceiling mount, as shown and described.
FIG. 1 is a perspective view from below of a ceiling mount in accordance with my design;
FIG. 2 is an enlarged perspective view from below of the ceiling mount in accordance with my design;
FIG. 3 is an enlarged side elevation view of the ceiling mount in accordance with my design, all sides being substantially identical to that shown; and,
FIG. 4 is an enlarged bottom plan view of the ceiling mount in accordance with my design.
The broken line showing of a ceiling fan is included for the purpose of illustrating environmental structure and forms no part of the claimed design.