sensor: pat9136: Add cooldown timer

This sensor may trigger data at a very fast pace (20,000 fps) and this
may not be useful for the application. Instead, it may affect its
proper functioning. Therefore, this patch includes a cool-down timer
before which time the INT line won't be enabled.

Please note that this sensor accumulates the delta compared to the
last reading, so on its own, not reading data-changes does not imply
losing data, as long as it does not saturate.

Signed-off-by: Luis Ubieda <luisf@croxel.com>