serial: 8250_exar: Return directly from switch-cases

serial: 8250_exar: Return directly from switch-cases

There are two similar switch-cases which use different style.
Unify them and one more to return from the cases directly.

While at it, add missing default in another switch-case.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Parker Newman <pnewman@connecttech.com>
Link: https://lore.kernel.org/r/20240503171917.2921250-10-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>