Nikkei slips on weak economic data; Sumitomo dives after profit warning

* Economic data, Hong Kong unrest weigh * Sumitomo's sharp decline hammers other trading houses * For the month, Nikkei is up 4.8 pct By Ayai Tomisawa TOKYO, Sept 30 (Reuters) - Japanese stocks fell on Tuesday morning as a one-two punch of weak economic data and a profit warning from Sumitomo Corp depressed sentiment. Investors were already on the back foot before the start of trading as pro-democracy protests in Hong Kong dented risk appetite in global markets. The ea