be2net: Call be_vf_setup() even when VFs are enbaled from previous load

Re-define the sriov_want() macro to check for number of VFs that need
to be enabled in the current load of the driver or the number of VFs that
still remain enabled from the previous load (attached VFs cannot be disabled.)

Signed-off-by: Vasundhara Volam <vasundhara.volam@emulex.com>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>