clk: imx: avoid memory leak

In case imx_register_uart_clocks return early, the imx_uart_clocks
memory will be no freed. So execute kfree always to avoid memory leak.

Fixes: 379c9a24 ("clk: imx: Fix reparenting of UARTs not associated with stdout")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/20230104110032.1220721-2-peng.fan@oss.nxp.com