bnx2: Clean up remaining iounmap

commit c0357e97 modified bnx2 to switch from
using ioremap/iounmap to pci_iomap/pci_iounmap.  They missed a spot in the error
path of bnx2_init_one though.  This patch just cleans that up.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Michael Chan <mcan@broadcom.com>
CC: "David S. Miller" <davem@davemloft.net>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>