clk: imx: constify clk_div_table

clk: imx: constify clk_div_table

clk_div_table are not supposed to change at runtime. All functions
working with clk_div_table provided by <linux/clk-provider.h> work
with const clk_div_table. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>