clk: visconti: Fix memory leak in visconti_register_pll()

In the Linux kernel, the following vulnerability has been resolved:

clk: visconti: Fix memory leak in visconti_register_pll()

@pll->rate_table has allocated memory by kmemdup(), if clk_hw_register()

fails, it should be freed, otherwise it will cause memory leak issue,

this patch fixes it.