Bluetooth: ATT: Fix not forwarding error properly

When retrying the request due to a security error that can fail but since
the original buffer was freed in the process the code can no longer verify
if the opcode matches thus it always fails BT_ATT_ERR_UNLIKELY instead of
using the response error, so this not longer cares about the opcode and
just use the response error always.

JIRA: ZEP-1195

Change-Id: I1149b993b97733ab5bb00f347e4f973647e0fdd4
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>