nfs-utils: clean up NFSCTL_* macros for handling protocol bits

They are a little hard to follow currently. Clean them up and add new
macros that can set these bits in addition to the ones that unset them.

Also add a new macro that reports when any valid protocol bit is set.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve Dickson <steved@redhat.com>