Channelflow: Fix the package. (#22483)

A search and replace went wrong in 2264e30d99.

Thanks to @wadudmiah who reported this issue.

var/spack/repos/builtin/packages/channelflow/package.py

@@ -69,7 +69,7 @@ def cmake_args(self):
         }
 
         args.append('-DWITH_NETCDF:STRING={0}'.format(
-            netcdf_str[spec.variants['netcdf-c'].value]
+            netcdf_str[spec.variants['netcdf'].value]
         ))
 
         # Set an MPI compiler for parallel builds