[Rootcanal] Miscellaneous bugfixes for SCO

Fix an inequality sign, and mask out the air coding bits from the voice
setting, since the spec says they don't have to match.

Bug: 245578454
Test: atest pts-bot:HFP
Ignore-AOSP-First: Cherry-picked from AOSP
Merged-In: I5627e28430f03f3978039485228a5abacf62ae58
Change-Id: I5627e28430f03f3978039485228a5abacf62ae58