I resolved marking the device as tested executing the following commands in the u-boot console:
# prepare in memroy
cp.b 0x9fff0000 0x81000000 0xffff
mw 0x81000050 0x646f6e65 # done
mw 0x81000060 0x7365636f # seco
# write to flash
protect off bank 1
cp.b 0x81000050 0x9fff0050 4 # done
cp.b 0x81000060 0x9fff0060 4 # seco
protect on bank 1
Now I am happy with my cool AR300M booting to NAND and/or NOR using the switch 