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/ramfs/file-mmu.c b/fs/ramfs/file-mmu.c
index 2f14774..97bdc0b 100644
--- a/fs/ramfs/file-mmu.c
+++ b/fs/ramfs/file-mmu.c
@@ -41,7 +41,7 @@
 	.aio_write	= generic_file_aio_write,
 	.mmap		= generic_file_mmap,
 	.fsync		= simple_sync_file,
-	.sendfile	= generic_file_sendfile,
+	.splice_read	= generic_file_splice_read,
 	.llseek		= generic_file_llseek,
 };