clk: versatile: free icst on error return

commit a183da63 introduced a new error return path that does
not kfree icst if the kmemdup of desc->params fails.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>