[PATCH] knfsd: SUNRPC: Add a function to format the address in an svc_rqst for printing

There are loads of places where the RPC server assumes that the rq_addr fields
contains an IPv4 address.  Top among these are error and debugging messages
that display the server's IP address.

Let's refactor the address printing into a separate function that's smart
enough to figure out the difference between IPv4 and IPv6 addresses.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: Aurelien Charbon <aurelien.charbon@ext.bull.net>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>