clk: renesas: r8a779a0: cpg_pll_configs should be __initconst

cpg_pll_configs[] is only used during initialization.  Hence make it
__initconst, so it will be freed later.

Fixes: 17bcc803 ("clk: renesas: cpg-mssr: Add support for R-Car V3U")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/a9819625329b188c298481402e1c55ac46093518.1720794214.git.geert+renesas@glider.be