* Islamic State claimed bombing of Shi'ite mosque on Friday * Shi'ite protesters say government does **t protect them * Interior Ministry says working to root out Islamic State (adds identity of attacker) By **ah Browning DUBAI, May 23 (Reuters) - Saudi Arabia's top Sunni cleric on Saturday branded a deadly attack on Shi'ite Muslims a bid to sow chaos, after villagers targeted in the bombing vented their anger at what they saw as the Sunni-dominated government's indifference to their safety. Thousands of protesters took to the streets of al-Qadeeh town on Friday evening, hours after a suicide bomber killed 21 worshippers in a packed Shi'ite mosque, the first attack in the conservative kingdom to be claimed by Islamic State militants.