knfsd: fix typo in export display, print uid and gid as unsigned

For display purposes, treat uid's and gid's as unsigned ints for now.
Also fix a typo.

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>