nfsd: allow choosing server 41 support at runtime

nfsd: allow choosing server 41 support at runtime

In the case where -N 4.1 is left off the commandline, the current code
explicitly turns it on or off anyway, depending on configure options.

Instead, just leave 4.1 support alone.  This allows a user to add an
"echo +4.1 >/proc/fs/nfsd/versions" to their init scripts, if they want.
Otherwise they will get the kernel's default (currently to leave 4.1
off, as long as 4.1 support is experimental).

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Steve Dickson <steved@redhat.com>