hwmon: (f71882fg) Cleanup sysfs attr creation 2/2

This patch merges the f71882fg_auto_pwm_attr array into the
fxxxx_fan_attr resp. fxxxx_auto_pwm_attr array, as the f71882fg_auto_pwm_attr
array was merely extending these 2 with entries for a 4th fan, it also makes
these 2 arrays 2 dimensional so that the rest of the code can choose to
add attr for 3 or 4 fans without needing to know the nr of attr per fan.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>