Remove dead code in checkForRingerModeChange

If mIsSingleVolume is true the checkForRingerModeChange will exit early
returning FLAG_ADJUST_VOLUME. Removed all if statements that cannot
evaluate to true because of mIsSingleVolume.

Test: manual check
Bug: 330414704
Change-Id: Icfc6b317397248fb25deda227a1d565b112bb631
1 file changed