Fix unsupported param code in cnvgrib - NCUM grib2 to grib1 conversion

[arulalant]

Edit params.f code of g2lib-1.4.0, so that cnvgrib -g21 option will be able to convert all NCUM grib2 params to grib1 param, without throwing any error.

[arulalant]

We fixed only 5 variables. Still need to support a lot more NCUM variables,