LU-10394 lnd: default to using MEM_REG

There is a performance drop when using IB_MR_TYPE_SG_GAPS. To
mitigate this, we added a module parameter, use_fastreg_gaps, which
defaults to 0. When allocating the memory region if this parameter
is set to 1 and the hw has gaps support then use it and output
a warning that performance may drop. Otherwise always use
IB_MR_TYPE_MEM_REG.

Test-Parameters: trivial
Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: I08a8b72756b9b5b5bcb391bf3e979f6d28eb5cbb
Reviewed-on: https://review.whamcloud.com/30749


Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Doug Oucharek <dougso@me.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>