With Wacom tablet mode-setting moved from userspace into kernel,
we don't have to consider failures of device queries through the
_raw callback as hard failure, as the driver can safely continue
anyway.

This is consistent with the current USB driver in wacom_sys.c
Reported-by: NPing Cheng <pinglinux@gmail.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>