By Hyonhee Shin SEOUL (Reuters) – North Korean leader Kim Jong Un has called for a propaganda campaign to increase popular support for the country’s ideology of self-reliance amid “the worst difficulties,” state media KCNA said on Tuesday. Kim sent a letter to ruling Workers’ Party officials attending a workshop on Monday that aimed to boost motivation for socialism and advance innovation in the party’s ideological work, KCNA said. In the dispatch, Kim said the party has been “advancing in the face of the worst difficulties” and stressed the need to spread its vision for “juche”, or self-relia…