Core clock "I" is sourced from CPG_PL1_DDIV divider as per HW manual
Rev.1.00.

This patch adds clock divider table "dtable_1_8" and switches to
DEF_DIV for "I" clock.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20211112081003.15453-3-biju.das.jz@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>