hwmon: (tmp421) Restore missing inputs

An off-by-one error caused some inputs to not be created by the driver
when they should. TMP421 gets only one input instead of two, TMP422
gets two instead of three, etc. Fix the bug by listing explicitly the
number of inputs each device has.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Tested-by: Andre Prendel <andre.prendel@gmx.de>
Cc: stable@kernel.org