qlcnic: Fix potential NULL dereference

[net-next:master 301/302] drivers/net/ethernet/qlogic/qlcnic/qlcnic_hw.c:563
 qlcnic_set_multi() error: potential null dereference 'cur'. (kzalloc returns null)

o Break out of the loop after memory allocation failure. Program all the
  MAC addresses that were cached in the return path.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Rajesh Borundia <rajesh.borundia@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>