Initialize SDP rmt_io_cap to UNKNOWN (0xFF)

* Set rmt_io_cap to 0xFF (Unknown) when initializing security device record
* Check if rmt_io_cap is unknown when processing passkey confirmation
  request and fail the confirmation if rmt_io_cap is never updated since
  record creation

Bug: 33269435
Test: BtStressTest:test_pair_bluetooth_stress
Change-Id: I329f3da37422d34548e4ef5d16fae4b5159fca22