pwmconfig: Print the initial PWM values

Print the initial PWM values before letting the user change them. This
should be useful to better understand what happens next, and for user
support in general.
pwmconfig: Raise the detection threshold to 3/4

Detection threshold of 2/3 of the maximum speed is too low, some fans
will slow down to about that speed so controlled fans may be missed.
Use 3/4 as the threshold to avoid these false negatives.
pwmconfig: Drop a stray comment

fancontrol supports multiple controlled fans for quite some time now.
pwmconfig: Properly deal with multiple fan control

When a given PWM output controls more than one fan,
fanactive_min is no longer a space-separated list of numbers, it will
also include items of the form "A+B". The tests in the rest of the
code do not expect that and choke with errors like:

/usr/sbin/pwmconfig: line 926: [: 538+799: integer expression expected
/usr/sbin/pwmconfig: line 952: [: 538+799: integer expression expected

As the only thing we really care about is whether any fan stops
completely when PWM is 0, we can simply record the minimum of the
lowest speed of all affected fans.
pwm: Declare local variables as such
Delete outdated document chips/MODPARMS.
Drop all outdated or redundant information from document chips/SUMMARY.
Move SMBus company ID list to a better place.