Bluetooth: Don't send public key if OOB data verification fails

When we receive the remote public key, if we have remote OOB data
there's no point in sending our public key to the remote if the OOB data
doesn't match. This patch moves the test for this higher up in the
smp_cmd_public_key() function.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>