Range limiting command for the Driving Force Pro wheel is only a FF_SPRING
effect so that the wheel creates resistance when the user tries to turn it past
the limit. It is however possible to overpower the FFB motors quite easily which
leads to the X axis value exceeding the expected limit. This confuses
games which dynamically adjust calibration using the highest/lowest min and max
values reported by the wheel. Joydev device driver also doesn't take in account
any changes in an axis range after the joystick device is created.

This patch recalculates received ABS_X axis value so it is always in
<0; 16383> range where 0 is the left limit and 16383 the right limit.
Logitech driver for Windows does the same thing.  As for any concerns about
possible loss of precision, I compared a large set of raw/adjusted values
generated by "mult_frac" to values returned by the Windows driver and I got
a 100% match.

Other Logitech wheels will probably need a similar fix, but I currently lack
the information needed to write one.
Signed-off-by: Michal Malý <madcatxster@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>