hwmon: f71882fg: add support for the Fintek F71808E

Allow device probing to recognise the Fintek F71808E.

Sysfs interface:
 * Fan/pwm control is the same as for F71889FG
 * Temperature and voltage sensor handling is largely the same as for
   the F71889FG
  - Has one temperature sensor less (doesn't have temp3)
  - Misses one voltage sensor (doesn't have V6, thus in6_input refers to
    what in7_input refers for F71889FG)

For the purpose of the sysfs interface fxxxx_in_temp_attr[] is split up
such that it can largely be reused.

Signed-off-by: Giel van Schijndel <me@mortis.eu>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>