Enable Khypervisor's proto2 on arndale board

1. Add board directory for arndale board.
2. Add Mct.c for enable Generic Timer. 
3. Delete BOARD_RTSMVE_CA15 predefine. Because already use VEXPRESS, ARNDALE predefine in boot.S. 
    So use VEXPRESS predefine instead of BOARD_RTSMVE_CA15.