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>

fs/jffs2/file.c

@@ -47,7 +47,7 @@ const struct file_operations jffs2_file_operations =
 	.ioctl =	jffs2_ioctl,
 	.mmap =		generic_file_readonly_mmap,
 	.fsync =	jffs2_fsync,
-	.sendfile =	generic_file_sendfile
+	.splice_read =	generic_file_splice_read,
 };
 
 /* jffs2_file_inode_operations */