ixgbe: Limit number of reported VFs to device specific value

ixgbe claims it supports 64 VFs in its SRIOV capability
structure, but the driver only supports 63.  Adjust it
so sysfs sriov configuration checking will check with
the proper totalvf value.

Signed-off-by: Donald Dutile <ddutile@redhat.com>
Acked-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>