By Sheila Dang and Katie Paul (Reuters) – Some major advertisers including Dyson, Mazda and chemicals company Ecolab have suspended their marketing campaigns or removed their ads from parts of Twitter because their promotions are appearing alongside tweets soliciting child pornography, the companies told Reuters. Ads for at least 30 brands, ranging from Walt Disney Co, Comcast Corp’s NBCUniversal and Coca-Cola Co. to a children’s hospital, have appeared on the profile pages of Twitter accounts that peddle links to the exploitative material, according to a Reuters review of accounts identified …