By Lucia Mutikani WASHINGTON (Reuters) – U.S. consumer sentiment slumped to its lowest level in nearly 11 years in early May as worries about inflation persisted, but consumer spending remains underpinned by a strong labor market and massive savings, which should keep the economy expanding. The University of Michigan’s survey on Friday showed the deterioration in sentiment was across all demographics, as well as geographical and political affiliation. Gasoline prices and the stock market have a heavy weighting in the survey. Gasoline prices resumed their upward trend this month, setting an ave…