fix npusim.sh ccopt-related typo

[GeorgeLin200100]

In npusim.sh:

# Using integer
USER_INTEGER=1
# Using float 
USER_FLOAT=0
# ...
if [[ $USE_INTEGER -eq 1 ]]; then
    ccopt+=" -DUSER_INTEGER"
fi
if [[ $USE_FLOAT -eq 1 ]]; then
    ccopt +=" -DUSER_FLOAT"
fi

USER_INTEGER VS. USE_INTEGER && USE_FLOAT VS. USER_FLOAT conflicts, causing ./npusim.sh build all failed with data_t.value not found. This PR fixed this issue.