clk: nxp: Declare mux table parameter as const u32 *

lpc18xx_fill_parent_names's "id" parameter isn't used for writing, so
let's make it const.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/20220205103613.1216218-3-j.neuschaefer@gmx.net


Signed-off-by: Stephen Boyd <sboyd@kernel.org>