clk: samsung: exynos990: Use PLL_CON0 for PLL parent muxes

clk: samsung: exynos990: Use PLL_CON0 for PLL parent muxes

Parent select bits for shared PLLs are in PLL_CON0, not PLL_CON3.
Using the wrong register leads to incorrect parent selection and rates.

Fixes: bdd03ebf721f ("clk: samsung: Introduce Exynos990 clock controller driver")
Signed-off-by: Denzeel Oliva <wachiturroxd150@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20250830-fix-cmu-top-v5-1-7c62f608309e@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>