Phase 3b, single arm, single site simplification study of HIV-1 infected patients with virological suppression under the combination of Lamivudine (150 mg BID) plus Raltegravir (400 mg BID) switching to Lamivudine (300 mg QD) plus Raltegravir (1200 mg QD): Roll-over study of the RALAM clinical trial (NCT02284035)