[Why]
dc_cursor_position do not initialise position.translate_by_source when
crtc or plane->state->fb is NULL. UBSAN caught this error in
dce110_set_cursor_position, as the value was garbage.

[How]
Initialise dc_cursor_position structure elements to 0 in handle_cursor_update
before calling get_cursor_position.
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1471Reported-by: NLyude Paul <lyude@redhat.com>
Signed-off-by: NAnson Jacob <Anson.Jacob@amd.com>
Reviewed-by: NAurabindo Jayamohanan Pillai <Aurabindo.Pillai@amd.com>
Acked-by: NSolomon Chiu <solomon.chiu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>