ixgbevf: Remove checking for mac.ops function pointers

The function pointers will always be set - there is no good reason to
check them.  Also just remove get_bus_info() call as the VF has no bus
info to report.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>