bnx2x: Prevent UNDI FW illegal host access

bnx2x: Prevent UNDI FW illegal host access

When loading after UNDI (e.g., Boot from SAN) the UNDI does not
gracefully yield its resources; The bnx2x driver handles that release
itself.

During the manipulation required to release those resources, it's possible
for the UNDI to try and write to memory regions which are no longer accessible,
causing the PCI bus to prevent further writes from the chip.

This would in turn cause DMAE timeouts later on in the driver, as the driver
will be unable to use the chip's DMA engines.

This patch prevents the chip from actually writing through the PCI bus
in said scenario, thus allowing the release without the unfortunate by-product.

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>