Fix validity date in title when step is 60m [MAGP-1362]

Author: iainrussell

src/decoders/GribDecoder.cc

@@ -159,11 +159,7 @@ long computeStep(const GribDecoder& grib, const string& key) {
         stepUnits["30Y"] = stepUnits["M"] * 30;
         stepUnits["C"]   = stepUnits["M"] * 100;
     }
-    string units;
-    if (grib.getstring("indicatorOfUnitOfTimeRange") == "m")
-        units = "m";
-    else
-        units = grib.getstring("stepUnits");
+    string units = grib.getstring("stepUnits");
 
     long step = grib.getLong(key);