bnx2x: Fix possible memory leak on iov error flow

Commit 2dc33bbc

 "bnx2x: Remove the sriov VFOP mechanism" introduced a possible
memory leak on the error flow during multicast filters configuration.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>