svcrpc: fix proc/net/rpc/auth.unix.ip/content display

Commit f15364bd ("IPv6 support for NFS
server export caches") dropped a couple spaces, rendering the output
here difficult to read.

(However note that we expect the output to be parsed only by humans, not
machines, so this shouldn't have broken any userland software.)

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>