bnx2x: add missing napi deletion in error path

If the hardware initialization fails in bnx2x_nic_load() after adding
napi objects, they would not be deleted. A subsequent attempt to unload
the bnx2x module detects a corruption in the napi list.

Add the missing napi deletion to the error path.

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Acked-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>