serial: sh-sci: Remove unused platform data capabilities field

The field isn't set by any platform but is only used internally in the
driver to hold data parsed from DT. Move it to the sci_port structure.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>