serial: 8250_dw: fix broken function call

The stub for dw8250_probe_acpi() is missing an argument.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>