bnx2x: Correct number of MSI-X vectors for VFs

Number of VFs in PCIe configuration space is zero-based. Driver incorrectly
sets the number of VFs to be larger by one than what actually is feasible by
HW, which might cause later VFs to fail to allocate their MSI-X interrupts.

Signed-off-by: Michal Kalderon <michals@broadcom.com>
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>