LU-2183 osp: cleanup osp-on-ost

LU-2183 osp: cleanup osp-on-ost

With new quota design and FIDonOST introduced, a new connection
from OST/MDTn to MDT0 is required for sending quota and sequence
RPCs. This connection was implemented by adding a new special
osp device named osp-on-ost, which introduced complexity to osp
code, and many hacks of checking the osp device name in both
client and server side code.

In this patch, we removed the osp-on-ost, and introduced a new
device type lwp (Light Weight Proxy) to manage the light weight
connection established from OSTs/MDTs to MDT0.

Signed-off-by: Niu Yawei <niu@whamcloud.com>
Signed-off-by: Wang Di <di.wang@whamcloud.com>
Change-Id: Ic1ba25f941a4f971a542dc4be8a81e28ee0f477b
Reviewed-on: http://review.whamcloud.com/4923
Tested-by: Hudson
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>