In the NFSv3 `fsinfo' procedure reply, don't claim that we support

In the NFSv3 `fsinfo' procedure reply, don't claim that we support
32k read and write operations on datagram sockets when in fact we
reject requests larger than 16k. It must be the case that virtually
all clients use data sizes of 16k or less for UDP transport (FreeBSD's
client defaults to 8k and never exceeds 16k), as this bug has been
present ever since NFSv3 support was added.

Reported by:	Senthil <lihtnes78@netscape.net>
Reviewed by:	dillon
Approved by:	re
MFC-after:	1 week