hwmon: (pmbus/ibm-cffps) max_power_out swap changes

The bytes for max_power_out from the ibm-cffps devices differ in byte
order for some power supplies.

The Witherspoon power supply returns the bytes in MSB/LSB order.

The Rainier power supply returns the bytes in LSB/MSB order.

The Witherspoon power supply uses version cffps1. The Rainier power
supply should use version cffps2. If version is cffps1, swap the bytes
before output to max_power_out.

Tested:
    Witherspoon before: 3148. Witherspoon after: 3148.
    Rainier before: 53255. Rainier after: 2000.

Signed-off-by: Brandon Wyman <bjwyman@gmail.com>
Reviewed-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20210928205051.1222815-1-bjwyman@gmail.com


[groeck: Replaced yoda programming]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>