clk: meson: c3: pll: Constify struct regmap_config

`clkc_regmap_config` is not modified and can be declared as const to
 move its data to a read-only section.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240703-clk-const-regmap-v1-4-7d15a0671d6f@gmail.com
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Author: javiercarrascocruz

drivers/clk/meson/c3-pll.c

@@ -678,7 +678,7 @@ static struct clk_regmap *const c3_pll_clk_regmaps[] = {
 	&mclk1,
 };
 
-static struct regmap_config clkc_regmap_config = {
+static const struct regmap_config clkc_regmap_config = {
 	.reg_bits       = 32,
 	.val_bits       = 32,
 	.reg_stride     = 4,