According to the device tree bindings for 8250, width is an optional property.
Default to 1 which is the same default value as used by the kernel.
Before this change the driver would not work for device trees which do not
include the optional binding.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>