Linux 2.6.35 compat, fops->fsync()

Linux 2.6.35 compat, fops->fsync()

The fsync() callback in the file_operations structure used to take
3 arguments.  The callback now only takes 2 arguments because the
dentry argument was determined to be unused by all consumers.  To
handle this a compatibility prototype was added to ensure the right
prototype is used.  Our implementation never used the dentry argument
either so it's just a matter of using the right prototype.