i40e: fix RSS queues only operating on PF0

This patch fixes the issue that RSS offloading only works on PF0 by
using the direct register writing of the hash keys for the VFs instead
of using the admin queue command to do so.

Change-ID: Ia02cda7dbaa23def342e8786097a2c03db6f580b
Signed-off-by: Lihong Yang <lihong.yang@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>