serial: sh-sci: Replace regmap array with port parameters

Turn the regmap two-dimensional array to an array of port parameters and
store a pointer to the port parameters in the sci_port structure. This
will allow handling additional port type dependent parameters.

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>