staging: lustre: ko2iblnd: Adapt to the removal of ib_get_dma_mr()

In Linux kernel 4.9-rc1, the function ib_get_dma_mr()
was removed and a second parameter was added to ib_alloc_pd().
As this broke the building of the ko2iblnd module in
staging, the Kconfig for LNet has marked ko2iblnd as broken
and stopped building it.

This patch fixes this breakage by:

- Removing the BROKEN tag from lnet/Kconfig.
- Make it so the module parameter map_on_demand can no longer be
  zero (we have to configure FMR/FastReg pools; it can no longer be
  off).
- No longer try to use the global DMA memory region, but make use
  of the FMR/FastReg pool for all RDMA Tx operations.
- Everywhere we are using the device DMA mr to derive the
  L-key for non-registered memory regions, use the
  pd->local_dma_lkey value instead.
- Make the default map_on_demand = 256.  This will allow nodes with
  this patch to still connected to older nodes without this patch
  and FMR/FastReg turned off.  When FMR/FastReg is turned off, we
  use 256 as the max frags so the two sides will still be able to
  communicate and work.
- Fix a mistake with BUILD_BUG_ON calls in o2iblnd.c which caused
  compiling to fail.

Signed-off-by: Doug Oucharek <doug.s.oucharek@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-9026
Reviewed-on: https://review.whamcloud.com/#/c/24931/


Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>