l2cap: Fix release p_ccb when not accepting channel

Do not use p_ccb to access p_lcb, since we are releasing it in the loop
and eventually it will get invalid.
Instead remember p_lcb at the beggining and use it directly.

Bug: 239678359
Test: atest BluetoothInstrumentationTests
Test: create EATT connections from remote side on unecrypted link
Tag: #feature
Change-Id: If94dc57679c60509f21263694ed16a1fd5e7c55d
Merged-In: If94dc57679c60509f21263694ed16a1fd5e7c55d