clk: xilinx: Constify struct regmap_config

`vcu_settings_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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/xilinx/xlnx_vcu.c

···
 	struct clk_hw_onecell_data *clk_data;
 };
 
-static struct regmap_config vcu_settings_regmap_config = {
+static const struct regmap_config vcu_settings_regmap_config = {
 	.name = "regmap",
 	.reg_bits = 32,
 	.val_bits = 32,