clk: imx: scu: use _safe list iterator to avoid a use after free

This loop is freeing "clk" so it needs to use list_for_each_entry_safe().
Otherwise it dereferences a freed variable to get the next item on the
loop.

Fixes: 77d8f306 ("clk: imx: scu: add two cells binding support")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/0793fbd1-d2b5-4ec2-9403-3c39343a3e2d@kili.mountain


Signed-off-by: Abel Vesa <abel.vesa@linaro.org>