mlxsw: pci: Fix reset wait for SwitchX2

SwitchX2 firmware does not implement reset done yet. Moreover, when
busy-polled for ready magic, that slows down firmware and reset takes
longer than the defined timeout, causing initialization to fail.
So restore the previous behaviour and just sleep in this case.

Fixes: 233fa44b ("mlxsw: pci: Implement reset done check")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>