nfsd4: expire clients more promptly

Expire clients more promptly, at the expense of possibly running the
laundromat thread more frequently.

Though it's not the default, I'd like it to be feasible to run with a
lease time of just a few seconds, at which point a minimum 10 second
wait between laundromat runs seems a little much.
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfsd.h

@@ -249,7 +249,7 @@ extern time_t nfsd4_grace;
 #define	COMPOUND_SLACK_SPACE		140    /* OP_GETFH */
 #define COMPOUND_ERR_SLACK_SPACE	12     /* OP_SETATTR */
 
-#define NFSD_LAUNDROMAT_MINTIMEOUT      10   /* seconds */
+#define NFSD_LAUNDROMAT_MINTIMEOUT      1   /* seconds */
 
 /*
  * The following attributes are currently not supported by the NFSv4 server: