sendfile: remove .sendfile from filesystems that use generic_file_sendfile()

They can use generic_file_splice_read() instead. Since sys_sendfile() now
prefers that, there should be no change in behaviour.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 7ed5639..ffcc504 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -2276,7 +2276,7 @@
 						    mounted filesystem. */
 	.mmap		= generic_file_mmap,	 /* Mmap file. */
 	.open		= ntfs_file_open,	 /* Open file. */
-	.sendfile	= generic_file_sendfile, /* Zero-copy data send with
+	.splice_read	= generic_file_splice_read /* Zero-copy data send with
 						    the data source being on
 						    the ntfs partition.  We do
 						    not need to care about the