Disable automatic dimming/blanking during incoming call

While there is an unanswered incoming call, power key can't be used
for display state control and therefore timer based dimmin/blanking
must not happen.

[mce] Disable automatic dimming/blanking during incoming call. Fixes JB#19194
Merge pull request #162 from spiiroin/incoming_call_blanking

Disable automatic dimming/blanking during incoming call