clk: renesas: rzv2h: Rename PLL field macros for consistency

clk: renesas: rzv2h: Rename PLL field macros for consistency

Rename PLL field extraction macros to include the associated register name
(`CPG_PLL_CLK1` or `CPG_PLL_CLK2`) to maintain consistency with other PLL
register macros. Update all corresponding macro references accordingly.

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/20250309211402.80886-5-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>