hwmon/pc87360: Convert to a platform driver

Convert the pc87360 driver from the nonsensical i2c-isa hack to a
regular platform driver. This is a direct conversion, other cleanups
could happen on top of that.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Jim Cromie <jim.cromie@gmail.com>