Bluetooth: Classic: SDP: Use slist to manage SDP records

Use slist instead of custom singly linked list to manage SDP records.

Check if the SDP record has been registered in the function
`bt_sdp_register_service()`.

Append the new SDP record to the tail of the SDP record list.

Check if the index of SDP record is overflow in the function
`bt_sdp_register_service()`.

Signed-off-by: Lyle Zhu <lyle.zhu@nxp.com>