NFS: Remove a redundant call to unmap_mapping_range()

We don't need to call unmap_mapping_range() prior to calling
nfs_sync_mapping().
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/inode.c

@@ -1170,7 +1170,6 @@ static int nfs_invalidate_mapping(struct inode *inode, struct address_space *map
 
 	if (mapping->nrpages != 0) {
 		if (S_ISREG(inode->i_mode)) {
-			unmap_mapping_range(mapping, 0, 0, 0);
 			ret = nfs_sync_mapping(mapping);
 			if (ret < 0)
 				return ret;