LE: Fix problem where pending command is not sent after pairing

If a read/write or other operation triggers SMP pairing with a remote
device, the operation should complete once pairing has finished. This
patch fixes a bug where the pending command was not sent after pairing.

Bug: 16405565
Change-Id: Idb2e54931c71b0a9e009cac318712eb9f5c7e15a