knfsd: cleanup of nfsd4 cmp_* functions

Benny Halevy suggested renaming cmp_* to same_* to make the meaning of
the return value clearer.

Fix some nearby style deviations while we're at it, including a small
swath of creative indentation in nfs4_preprocess_seqid_op().

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Acked-by:  Neil Brown <neilb@suse.de>