LU-7225 llite: ladvise protocol changes

LU-7225 llite: ladvise protocol changes

This patch makes some changes to the ladvise API and
protocol to support lock ahead and possible future users.

Primarily, it separates the userspace API arguments from
the structures which go out on the network, and adds a
number of 'value' fields without a predefined use.

The meaning of each value field can be different for
different advice types, allowing some extensibility.

Signed-off-by: Patrick Farrell <paf@cray.com>
Change-Id: I7ac18e546f16a20c3c6bc6849becb0d45e3d5dc9
Reviewed-on: http://review.whamcloud.com/20666
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>