1. Add a R/W attribute "update_interval". By default, it is set to 1000ms.

This defines the minimum interval occ driver poll occ for latest sensor data.
When reading occ hwmon attributes within the update_interval, the driver
will no poll occ and it returns sendor data from cached data.

You can do e.g. "echo 5000 > /sys/class/hwmon0/update_interval" to change it to 5000ms.

2. Revise code based on Jeremy's comments.
The driver name is changed to occ_i2c.c

3. This patch will be removed when the occ_i2c driver is merged into Linux tree.

Author: adamliyi