Input: elan_i2c - increment wakeup count if wake source

Notify the PM core that this device is the wake source. This helps
userspace daemon tracking the wake sources to identify the origin of the
wake.

Signed-off-by: Ravi Chandra Sadineni <ravisadineni@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>