xmonad: amixer: decrement 1dB at a time
xmonad: amixer: decrement 1dB at a time

Apparently, the old way of decrementing 1.5dB at a time would make it
decrement 2dB on exelion; decrementing 1dB at a time makes it behave
properly on exelion (while still behaving the same way on luxion, which
uses 1.5dB steps).

listx/syscfg,listx/syscfg,listx/syscfg,listx/syscfg,listx/syscfg