ixgbevf: fix possible use of uninitialized variable

This patch resolves the following warning:

drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c: In function ‘ixgbevf_probe’:
drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c:1742:290: warning: ‘err’ may be used uninitialized in this function [-Wuninitialized]
drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c:1717:6: note: ‘err’ was declared here

Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>