[Yaffs] YAFFS2 commit_write return 0 for success

Return zero, not number of bytes written, for success (and non-zero for
error) in the commit_write method. Some callers, notably the loopback
mount driver, treat non-zero return as an error.

Signed-off-by: Todd Poynor <tpoynor@mvista.com>

Index: yaffs_fs.c
===================================================================
RCS file: /home/aleph1/cvs/yaffs2/yaffs_fs.c,v
retrieving revision 1.31
diff -u -r1.31 yaffs_fs.c
--- yaffs_fs.c    21 Sep 2005 01:14:03 -0000    1.31
+++ yaffs_fs.c    19 Oct 2005 06:58:36 -0000
@@ -604,9 +604,10 @@
     }

     T(YAFFS_TRACE_OS,
-      (KERN_DEBUG "yaffs_commit_write returning %d\n", nWritten));
+      (KERN_DEBUG "yaffs_commit_write returning %d\n", 
+       nWritten == nBytes ? 0 : -1));

-    return nWritten;
+    return nWritten == nBytes ? 0 : -1;

}