scope of resentencing on remand after sentence of mandatory life without parole (LWOP) for a juvenile is vacated in light of Miller v. Alabama; trial court did not err in failing to disturb unrelated consecutive sentences for armed robbery on remand from vacated LWOP sentence for felony murder; argument regarding propriety of consecutive sentences for unrelated convictions aggregated with vacated LWOP sentence for felony murder was waived where counsel conceded unrelated convictions were not before the court at resentencing; ineffective assistance of counsel claim regarding consecutive sentences for felony murder and kidnapping failed because the defendant could not demonstrate make required showing of prejudice; court declined to address and dismissed without prejudice ineffective assistance of counsel claim regarding Miller's prohibition against disproportionate punishment for juvenile offenders under the Eighth Amendment by imposing LWOP because of conflicting opinions regarding the constitutionality of de facto LWOP sentences for juveniles and pendency of appeal before North Carolina Supreme Court that will resolve this issue