nfsd: move most of nfsfh.h to fs/nfsd

Most of this can be trivially moved to a private header as well.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index 7d5ba1b..b26a364 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -22,6 +22,7 @@
 #include <net/ipv6.h>
 
 #include "nfsd.h"
+#include "nfsfh.h"
 
 #define NFSDDBG_FACILITY	NFSDDBG_EXPORT