LU-6215 llite: handle new_sync_[read|write] removal

LU-6215 llite: handle new_sync_[read|write] removal

In newer linux kernel version the file read/write
API have been moving to using struct iov_iter. To
continue supporting the old API new wrapper
functions were created, new_sync_*, which allowed
the use of the new API's to support the old API's.
For the linux 4.1 kernel those new_sync_* are used
internally so they are no longer exposed to any
file systems. If a file system wants to use the
"old" api they need to call vfs_[write|read].
Update lustre to handle this change. The upstream
commit that made new_sync_* internal was:

Linux commit: 5d5d568975307877e9195f5305f4240e506a2807

Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Change-Id: Ibf69d25af8a7d5cda00c5b1be4757ec369e8e814
Reviewed-on: http://review.whamcloud.com/15165
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>