dt-bindings: clock: r9a07g044-cpg: Add entry for P0_DIV2 core clock

dt-bindings: clock: r9a07g044-cpg: Add entry for P0_DIV2 core clock

Add P0_DIV2 core clock required for CANFD module. CANFD core clock is
sourced from P0_DIV2 referenced from HW manual Rev.0.50.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20210719143811.2135-4-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>