clk: rockchip: Switch to use kmemdup_array()

Let the kememdup_array() take care about multiplication and possible
overflows.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240606161028.2986587-3-andriy.shevchenko@linux.intel.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>