check p_db pointer for NULL check

since during incoming sdp connection and query , p_db could be NULL.
Cherry-pick from wear os

Bug: 263323082
bug: 264015001
Test: manual pairing and connection test with phone
Change-Id: Ie55894fe36fc288f64576e21690bd404c8317565
(cherry picked from commit a0f97071dba4a1798091717f93bc4cee23244334)