This driver calls ioremap() in probe, but it misses calling iounmap() in
probe's error handler and remove.
Add the missed calls to fix it.

Fixes: 47d37d6f ("serial: Add auart driver for i.MX23/28")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200709135608.68290-1-hslester96@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>