Input: wacom_w8001 - report resolution to userland

Serial devices send both pen and touch data through the same logical
port. Since we scaled touch to pen maximum, we use pen resolution
for touch as well here.

This is under the assumption that pen and touch share the same physical
surface. In the case when a small physical dimensional difference occurs
between pen and touch, we assume the tolerance for touch point precision
is higher than pen and the difference is within touch point tolerance.

A per-MT tool based resolution mechanism should be introduced if the
above assumption does not hold true for the pen and touch devices any
more.

Signed-off-by: Ping Cheng <pingc@wacom.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>