serial: ifx6x60: add missed pm_runtime_disable

The driver forgets to call pm_runtime_disable in remove.
Add the missed calls to fix it.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191118024833.21587-1-hslester96@gmail.com


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