Bluetooth: ISO: Clean up returns values in iso_connect_ind()

This function either returns 0 or HCI_LM_ACCEPT.  Make it clearer which
returns are which and delete the "lm" variable because it is no longer
required.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>