Revert "serial: sh-sci: Add support for RZ/G2L SoC"

This reverts commit 064b6e47b2b2d4a20566ba6f8dc90e46b599b35f as it
wasn't quite ready yet :(

Cc: Biju Das <biju.das.jz@bp.renesas.com>
CC: Geert Uytterhoeven <geert+renesas@glider.be>
Reported-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>