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 a bottom plan view of the ceiling mount in accordance with my design;
FIG. 3 is a front elevation view of the ceiling mount in accordance with my design, the opposite side being a mirror image thereof; and,
FIG. 4 is a side elevation view taken at a 45 degree angle of the ceiling mount in accordance with my design, the opposite side being a mirror image thereof.
The broken lines showing environmental structure are for illustrative purposes and form no part of the claimed design.