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/fat/file.c b/fs/fat/file.c
index 55d3c74..69a83b5 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -134,7 +134,7 @@
 	.release	= fat_file_release,
 	.ioctl		= fat_generic_ioctl,
 	.fsync		= file_fsync,
-	.sendfile	= generic_file_sendfile,
+	.splice_read	= generic_file_splice_read,
 };
 
 static int fat_cont_expand(struct inode *inode, loff_t size)