magister: modify ADC volume button thresholds
magister: modify ADC volume button thresholds

change volume up/down of ADC thresholds value.

BUG=b:167319238
BRANCH=master
TEST=Press Vol+- button function work.

Change-Id: Iddb688832ca5bd343c9e6b577cd129c0895fd7dc
Signed-off-by: Ben Chen <e0a434a5da0616e0b8100476444b79aeee435f0d@quanta.corp-partner.google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2952283
Reviewed-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>
Commit-Queue: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec