hwmon (occ): Parse OCC poll response

Add method to parse the response from the OCC poll command. This only
needs to be done during probe(), since the OCC shouldn't change the
number or format of sensors while it's running. The parsed response
allows quick access to sensor data, as well as information on the
number and version of sensors, which we need to instantiate hwmon
attributes.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>