ocfs2: Remove EXIT from masklog.

mlog_exit is used to record the exit status of a function.
But because it is added in so many functions, if we enable it,
the system logs get filled up quickly and cause too much I/O.
So actually no one can open it for a production system or even
for a test.

This patch just try to remove it or change it. So:
1. if all the error paths already use mlog_errno, it is just removed.
   Otherwise, it will be replaced by mlog_errno.
2. if it is used to print some return value, it is replaced with
   mlog(0,...).
mlog_exit_ptr is changed to mlog(0.
All those mlog(0,...) will be replaced with trace events later.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>

fs/ocfs2/mmap.c

@@ -55,7 +55,7 @@ static int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)
 	ret = filemap_fault(area, vmf);
 	ocfs2_unblock_signals(&oldset);
 
-	mlog_exit_ptr(vmf->page);
+	mlog(0, "%p\n", vmf->page);
 	return ret;
 }