NFS: Fix sparse warnings

Fix the following sparse warnings:

fs/nfs/direct.c:221:6: warning: symbol 'nfs_direct_readpage_release' was
not declared. Should it be static?
fs/nfs/read.c:38:43: warning: non-ANSI function declaration of function
'nfs_readhdr_alloc'
fs/nfs/objlayout/objio_osd.c:214:5: warning: symbol '__alloc_objio_seg'
was not declared. Should it be static?

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Fred Isaman <iisaman@netapp.com>
Cc: Boaz Harrosh <bharrosh@panasas.com>
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 37c9eb2..f23cf25 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -35,7 +35,7 @@
 
 static struct kmem_cache *nfs_rdata_cachep;
 
-struct nfs_read_header *nfs_readhdr_alloc()
+struct nfs_read_header *nfs_readhdr_alloc(void)
 {
 	struct nfs_read_header *rhdr;