i40e: Add message for unsupported MFP mode

i40e: Add message for unsupported MFP mode

This patch adds a check and message if the device is in
MFP mode as changing RSS input set is not supported in
MFP mode.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 26785018
(cherry picked from commit 83d14c595e011f96c47e5fb09ddb51902e8367aa)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Kyle Fortin <kyle.fortin@oracle.com>