serial: 8250_dw: Use a unified new dev variable in remove

serial: 8250_dw: Use a unified new dev variable in remove

The commit 99bad0751b89 ("serial: 8250_dw: Use a unified new dev variable in
probe") introduced a local dev variable in ->probe(). Do the same in ->remove()
in order to prepare for sequential patches.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Link: https://lore.kernel.org/r/20190806094322.64987-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>