hwmon: fix array overruns in lm93.c

This fixes an array overflow bug. We have 4 pairs of min/max temperature
limits, not 3.

Signed-off-by: Hans J. Koch <hjk@linutronix.de>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>