MEXICO CITY (Reuters) – British far-right activist Tommy Robinson said he was detained upon arrival with his children at Mexico’s Cancun airport and will be deported, according to a video he posted Saturday. Robinson, co-founder of the English Defence League (EDL) which has staged violent demonstrations against Islam, said he was arrested and separated from his three children. He had been detained for a couple of days, he said, without noting when he landed. “Now, I’m being deported as a matter of national security,” Robinson said in an apparent selfie video taken inside a room and posted on t…