clk: meson: a1: pll: Constify struct regmap_config

`a1_pll_regmap_cfg` 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-v1-2-7d15a0671d6f@gmail.com
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Author: javiercarrascocruz

drivers/clk/meson/a1-pll.c

@@ -295,7 +295,7 @@ static struct clk_regmap *const a1_pll_regmaps[] = {
 	&hifi_pll,
 };
 
-static struct regmap_config a1_pll_regmap_cfg = {
+static const struct regmap_config a1_pll_regmap_cfg = {
 	.reg_bits   = 32,
 	.val_bits   = 32,
 	.reg_stride = 4,