By Peter Nicholls DOVER, England (Reuters) -A man threw petrol bombs attached to fireworks at a centre for processing migrants in the southern English port of Dover on Sunday and then killed himself, a Reuters photographer said. The attacker, a white man in a checked shirt, drove up to the centre in a white SEAT sports utility vehicle at around 1120 GMT. He got out and threw three petrol bombs, one of which failed to go off, the photographer said. He then drove to a nearby petrol station, tied an improvised noose around his neck, attached it to a metal pole and drove off, killing himself, the …