nfscl: Make coverity happy

Coverity does not like code that checks a function's
return value sometimes. Add "(void)" in front of the
function when the return value does not matter to try
and make it happy.

A recent commit deleted "(void)"s in front of nfsm_fhtom().
This commit puts them back in.

(cherry picked from commit 695d87bae1ec826fcf796f99b9de9cdd8c37fb8c)