sh: Don't set sh-sci port_reg

sh: Don't set sh-sci port_reg

The driver considers all negative or zero values of the port_reg field
as invalid. The four platforms that set the field to a register address
all use an address higher than 0x7fffffff, which is thus considered by
the driver as invalid. The feature is thus never used, remove it.

The feature could be implemented properly in the future using the
pinctrl and GPIO APIs if desired.

While at it, don't set the field to SCIx_NOT_SUPPORTED (-1) either,
leaving it unset leads to the same result. This will allow removing the
SCIx_NOT_SUPPORTED macro.

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>