hwmon: (it87) Split temperature sensor detection to separate function

The temperature sensor type will need to be used in multiple places, so
split it out into its own function.

Signed-off-by: Frank Crawford <frank@crawford.emu.id.au>
Link: https://lore.kernel.org/r/20230707123005.956415-2-frank@crawford.emu.id.au


[groeck: Dropped unnecessary 'type' variable in show_temp_type()]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>