staging: lustre: llite: set security xattr using __vfs_setxattr

Currently ll_initxattrs() initializes the security xattrs in
a very non-standard using get_xattr_types() to get the struct
handler that lustre created to then call indirectly the function
to set the xattr. The available __vfs_setxattr() function does
the same thing and also handles the case of when size is zero
the xattr should be set to empty EA.

Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-9183
Reviewed-on: https://review.whamcloud.com/27240


Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>