LU-5718 o2iblnd: multiple sges for work request

LU-5718 o2iblnd: multiple sges for work request

In current protocol, lnet router cannot align buffer for rdma,
o2iblnd may run into "too fragmented RDMA" issue while routing
non-page-aligned IO larger than 512K, because each page will
be splited into two fragments by kiblnd_init_rdma().

With this patch, o2iblnd can have multiple sges for each work
request, and combine multiple remote fragments of the same page
into one work request to resovle the "too fragmented RDMA" issue.

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Change-Id: Id57a74dc92801b012956ab785233aa87cac14263
Reviewed-on: https://review.whamcloud.com/12451
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>