Phosphonic acid,[2-[[[7-(cyclohexylamino)-1-(1-ethylpropyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinolinyl]carbonyl]amino]-1,1-difluoroethyl]-,mono[(5-methyl-2-oxo-1,3-dioxol-4-yl)methyl] ester