drm: fix drm_display_info_set_bus_formats kernel doc header

formats and num_formats arguments were previously called fmts and nfmts.
Fix the kernel doc comment so that it matches the new argument names.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>