clk: renesas: rzv2h: Drop redundant base pointer from pll_clk

clk: renesas: rzv2h: Drop redundant base pointer from pll_clk

The base address can be accessed via the priv pointer already present in
struct pll_clk, making the separate base field redundant. Remove the base
member and its assignment.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250624153049.462535-1-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>