Add vdd core regulator (1.1 V) for GPU.

This patch add regulator support for GPU.

The H/W manual mentions nothing about a GPU regulator. So using vdd
core regulator for GPU.
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/20220307192436.13237-4-biju.das.jz@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>