Clean up: mount option parsing uses kstrndup in several places, rather than
using kzalloc.  Replace the few remaining uses of kzalloc with kstrndup,
for consistency.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>