board: renesas: Remove empty s_init function

Default s_init weak function available, so remove the
s_init empty function.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
5 files changed