mlxsw: pci: Implement reset done check

Firmware now tells us that the reset is done by passing a magic value
via register. Use it to shorten the wait in case this is supported.
With old firmware, we still wait until the timeout is reached.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>