CHROMIUM: Input: atmel_mxt_ts - warn if sysfs could not be created

CHROMIUM: Input: atmel_mxt_ts - warn if sysfs could not be created

If sysfs entry creation fails, the driver is still usable, so don't
just abort probe.  Just warn and continue.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
BUG=chrome-os-partner:8733
TEST=builds clean

Change-Id: I67073b9ee773379395f8f9bbea3cd0163d7066ca
Reviewed-on: https://gerrit.chromium.org/gerrit/20846
Commit-Ready: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>