drm/dp_mst: Simplify character output in drm_dp_mst_dump_topology()

drm/dp_mst: Simplify character output in drm_dp_mst_dump_topology()

Single characters should be put into a sequence.
Thus use the corresponding function “seq_putc” for one selected call.

This issue was transformed by using the Coccinelle software.

Suggested-by: Christophe Jaillet <[email protected]>
Signed-off-by: Markus Elfring <[email protected]>
Reviewed-by: Lyude Paul <[email protected]>
Signed-off-by: Lyude Paul <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]