tty: serial: uartlite: use clk_disable_unprepare to match clk_prepare_enable

The driver uses clk_prepare_enable in ulite_probe but uses clk_unprepare
in ulite_remove, which does not match.
Replace clk_unprepare with clk_disable_unprepare to fix it.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Link: https://lore.kernel.org/r/20191101085433.10399-1-hslester96@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>