clk: lan966x: make clk_names const char * const

Change clk_names to const char * const to silence checkpatch in
subsequent patches.

Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Link: https://lore.kernel.org/r/20240916-lan969x-clock-v1-2-0e150336074d@microchip.com


Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>