Input: wacom_w8001 - allocate additional space for 'phys'

GCC warns that the output of our call to 'snprintf' in 'w8001_connect'
may be truncated since both 'serio->phys' and 'w8001->phys' are 32 bytes
in length. Increase the amount of space allocated for the latter to
compensate.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>