i40e: Don't register/de-register apps on NIC partitions in MFP mode

Do not register or try to de-register DCB applications with the DCBNL
layer in case of NIC partitions when adapter is in MFP mode.

Change-ID: I603d042a61983a6562be471c6a2b181572504118
Signed-off-by: Neerav Parikh <neerav.parikh@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>