platform/chrome: sensorhub: Bound the EC-reported sensor number

In the Linux kernel, the following vulnerability has been resolved: platform/chrome: sensorhub: Bound the EC-reported sensor number Each EC FIFO event carries an 8-bit sensor number (in->sensor_num). cros_ec_sensorhub_ring_handler() validates the FIFO event count, the per-read count and the ring bound, but not the sensor number, which cros_ec_sensor_ring_process_event() then uses unchecked to index sensorhub->batch_state[] - allocated with only sensorhub->sensor_num entries. A sensor number of sensor_num or larger is an out-of-bounds read and write of batch_state[]. Validate the sensor number in the ring handler, where each event is read from the EC, and drop a malformed event before it is used.