fix parsing and remove stderr from output

[phuclv90]

I have a simpler method to split here https://github.com/jlhonora/lsusb/pull/23

-devices=`echo "$rawlog" | egrep -B 2 -A 6 "Product ID" | sed 's/^--/#/'`
+devices=`echo "$rawlog" | sed -e '/:$/i\
+#'`