Root-Canal: Use kReservedHandle for invalid SCO handles

- Used handle 0 as invalid SCO handle instead of kReservedHandle,
  caused asserts to fail in ACL disconnect following SCO disconnect
- Fix bug in SCO link parameter negotiation which caused parameter
  sets using the fukk bandwidth to be rejected

Test: PTS test HFP/HF/ACS/BV-07-I against Eiffel stack
Change-Id: Ieb227a8a940e8e86138e349bece94a26092b3c65