bnx2x: Wait for MCP validity during AER

During PCIe advanced error recovery, the secondary bus reset will cause FW
to reset; This will cause the shared memory between it and the driver to be
invalidated.

During the driver's recovery flow, the driver should not make any assumption
on the validity of that memory and instead re-initialize it.

This also removes a redundant re-initialization of a previously
initialized mutex.

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>