lineage-sdk: Fix missed call LED color settings support

* Add support for dedicated missed call LED settings when custom values are enabled
* Only check dedicated phone/voicemail LED settings when custom LED values are enabled
* Preserve alpha channel during brightness scaling to prevent color corruption
* Fixes issue where custom missed call LED colors were ignored

Change-Id: I97a8f5e63d31276dd0a61e4180a990fbfed154f7
Signed-off-by: Jackeagle <jackeagle102@gmail.com>