LU-9828 ptlrpc: Do not assert when bd_nob_transferred != 0

LU-9828 ptlrpc: Do not assert when bd_nob_transferred != 0

There is a case in the routine ptlrpc_register_bulk() where we were
asserting if bd_nob_transferred != 0 when not resending.  There is
evidence that network errors can create a situation where
this does happen.  So we should not be asserting!

This patch changes that assert to an error return code of -EIO.

Signed-off-by: Doug Oucharek <doug.s.oucharek@intel.com>
Change-Id: I6a73ca1b04a86f187744d3b8b5d46df71d95e416
Reviewed-on: https://review.whamcloud.com/28491
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Sonia Sharma <sonia.sharma@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>